Implement direct encap transport parameter negotiation + Fix build errors

Summary:
This diff implements the transport parameter negotiation logic for direct encapsulation support on top of D77604174, addresses reviewer feedback by changing the connection state pointer to a reference, and **fixes critical build errors** caused by the constructor signature changes.

**Changes Made:**

1. **Client-side logic**: The client sends the `client_direct_encap` transport parameter with no value if `supportDirectEncap` is true.

2. **Server-side logic**: The server sends the `server_direct_encap` transport parameter if `directEncapAddress` is not null AND the client sent the `client_direct_encap` parameter. The value is the IP address bytes in network byte order.

3. **Pointer to Reference Change**: Changed `const QuicConnectionStateBase* conn_` to `const QuicConnectionStateBase& conn_` in ServerTransportParametersExtension as requested by reviewer feedback, since nullability is not possible (non-null is an invariant).

4. **🔧 Build Error Fixes**: Fixed multiple test files that were broken by the constructor signature changes:

**Build Fixes Applied:**

- **Fixed 3 critical build failures** that prevented compilation:
  - `fbcode//quic/facebook/mbed/test:mbed_client_handshake`
  - `fbcode//quic/fizz/client/handshake/test:fizz_client_handshake_test`
  - `fbcode//quic/server/handshake/test:ServerHandshakeTest`

- **Updated constructor calls** in test files to include the new `const QuicConnectionStateBase& conn` parameter
- **Fixed helper functions** like `constructServerTp()` to accept and pass connection state
- **Updated test classes** like `MalformedServerTransportParamsExt` to handle the new parameter

**Files Fixed:**
- `fbcode/quic/facebook/mbed/test/MbedClientHandshake.cpp` - Fixed 4 constructor calls and helper functions
- `fbcode/quic/fizz/client/handshake/test/FizzClientHandshakeTest.cpp` - Fixed constructor call
- `fbcode/quic/server/handshake/test/ServerHandshakeTest.cpp` - Fixed constructor call

**Test Results:**
- ✅ `buck test fbcode//quic/facebook/mbed/test:mbed_client_handshake` → Pass 7, Fail 0
- ✅ `buck test fbcode//quic/fizz/client/handshake/test:fizz_client_handshake_test` → Pass 12, Fail 0
- ✅ All previously failing builds now compile successfully

**Implementation Details:**

- Added `encodeIPAddressParameter()` function to handle IP address encoding (supports both IPv4 and IPv6)
- Modified `getSupportedExtTransportParams()` to include client-side direct encap logic
- Created new `getClientDependentExtTransportParams()` function that specifically handles server-side direct encap logic based on client parameters
- Updated `ServerTransportParametersExtension` to use the new function for adding client-dependent parameters
- Updated `ServerStateMachine` to pass connection state to the extension
- **Changed constructor parameter order**: `conn` parameter now comes before `customTransportParameters` to maintain C++ default parameter rules
- **Updated member initialization order**: Fixed to match class declaration order
- **Fixed all test constructors**: Updated test cases to provide connection state parameter

**Architecture:**

Instead of overloading `getSupportedExtTransportParams()` with two parameters, the solution now uses a dedicated `getClientDependentExtTransportParams()` function that:
- Only handles parameters that depend on client capabilities (currently `server_direct_encap`)
- Returns a clean list of parameters without duplicating base transport parameters
- Provides better separation of concerns and clearer function naming

**Unit Tests Added:**

- Comprehensive test suite in `fbcode/quic/handshake/test/TransportParametersTest.cpp`
- 8 test cases covering all client/server scenarios with IPv4/IPv6 support
- Tests verify parameter presence/absence and correct IP address byte encoding
- All tests pass successfully
- **Updated test infrastructure**: Fixed ServerTransportParametersTest.cpp to work with reference-based connection state

**Requirements Fulfilled:**
✅ Client sends `client_direct_encap` parameter with no value if `supportDirectEncap` is true
✅ Server sends `server_direct_encap` parameter with IP address bytes if conditions are met
✅ Changed connection state from pointer to reference as requested by reviewer
✅ **Fixed all build errors caused by constructor signature changes**
 ---
> Generated by [RACER](https://www.internalfb.com/wiki/RACER_(Risk-Aware_Code_Editing_and_Refactoring)/), powered by [Confucius](https://www.internalfb.com/wiki/Confucius/Analect/Shared_Analects/Confucius_Code_Assist_(CCA)/)
[Session](https://www.internalfb.com/confucius?entry_name=RACER&mode=Focused&namespace[0]=agentrix&session_id=8c84b14a-56a5-11f0-8e69-214e73924e50&tab=Chat), [Trace](https://www.internalfb.com/confucius?entry_name=RACER&mode=Focused&namespace[0]=agentrix&session_id=8c84b14a-56a5-11f0-8e69-214e73924e50&tab=Trace)
[Session](https://www.internalfb.com/confucius?entry_name=RACER&mode=Focused&namespace[0]=agentrix&session_id=439da8ee-5798-11f0-ace1b7dae9e7575d&tab=Chat), [Trace](https://www.internalfb.com/confucius?entry_name=RACER&mode=Focused&namespace[0]=agentrix&session_id=439da8ee-5798-11f0-ace1-b7dae9e7575d&tab=Trace)
[Session](https://www.internalfb.com/confucius?session_id=7ed2dc86-5847-11f0-8055-b73b775dc61a&tab=Chat), [Trace](https://www.internalfb.com/confucius?session_id=7ed2dc86-5847-11f0-8055-b73b775dc61a&tab=Trace)
[Session](https://www.internalfb.com/confucius?session_id=8bdc0a0c-584b-11f0-9977-35e1e0d6200a&tab=Chat), [Trace](https://www.internalfb.com/confucius?session_id=8bdc0a0c-584b-1f0-9977-35e1e0d6200a&tab=Trace)
**[Current Session](https://www.internalfb.com/confucius?session_id={{ session_id }}&tab=Chat), [Trace](https://www.internalfb.com/confucius?session_id={{ session_id }}&tab=Trace)**
[Session](https://www.internalfb.com/confucius?entry_name=RACER&mode=Focused&namespace[0]=agentrix&session_id=08290174-5b4d-11f0-ac9d-93447239bce3&tab=Chat), [Trace](https://www.internalfb.com/confucius?entry_name=RACER&mode=Focused&namespace[0]=agentrix&session_id=08290174-5b4d-11f0-ac9d-93447239bce3&tab=Trace)
[Session](https://www.internalfb.com/confucius?entry_name=RACER&mode=Focused&namespace[0]=agentrix&session_id=ded2f5f2-5b6d-11f0-b259-5db72d7f2f63&tab=Chat), [Trace](https://www.internalfb.com/confucius?entry_name=RACER&mode=Focused&namespace[0]=agentrix&session_id=ded2f5f2-5b6d-11f0-b259-5db72d7f2f63&tab=Trace)

Reviewed By: hanidamlaj

Differential Revision: D77605298

fbshipit-source-id: 22d3faffaa93f1aa57e05c984339ab3b2e817ac1

quic/server/state/ServerStateMachine.cpp

@@ -1030,6 +1030,7 @@ folly::Expected<folly::Unit, QuicError> onServerReadDataFromOpen(
             *newServerConnIdData->token,
             conn.serverConnectionId.value(),
             initialDestinationConnectionId,
+            conn,
             customTransportParams));
     conn.transportParametersEncoded = true;
     const CryptoFactory& cryptoFactory =