Convert IntervalSet from throwing exceptions to using CHECKs with Expected error handling

Summary:
This commit converts IntervalSet to use CHECKs instead of throwing exceptions and provides safe tryInsert methods that return quic::Expected for error handling.

**Core Problem Solved:**
IntervalSet was throwing `std::invalid_argument` exceptions in two scenarios:
1. When constructing an Interval with `start > end`
2. When interval bounds exceed the maximum allowed value

This change eliminates exceptions in favor of CHECKs (for internal validation) and Expected-based error handling (for caller validation).

**Implementation Details:**

**1. IntervalSet Core Changes:**
- Replaced `throw std::invalid_argument` with `CHECK_LE` in Interval constructor
- Replaced `throw std::invalid_argument` with `CHECK_LE` in `insert(start, end)`
- Added `IntervalSetError` enum for error classification
- Added `folly::Expected` include

**2. Safe API Layer:**
- Added `tryInsert(interval)` method returning `Expected<Unit, IntervalSetError>`
- Added `tryInsert(start, end)` method with pre-validation
- Added `tryInsert(point)` method
- Added static `Interval::tryCreate()` method for safe interval construction

**3. Updated  Code:**
- **QuicWriteCodec.cpp**: Updated `fillFrameWithPacketReceiveTimestamps` to use `tryInsert`
  - Returns `QuicError` if interval validation fails
  - Maintains existing error handling patterns
- **QuicTransportFunctions.cpp**: Updated `implicitAckCryptoStream` to use `tryInsert`
  - Logs errors and continues processing other packets
  - Robust error handling for crypto stream implicit acks

Reviewed By: kvtsoy

Differential Revision: D76792362

fbshipit-source-id: 5bd7c22e69a91d60cc41c603a1f2380893f4c8a0

quic/server/state/ServerStateMachine.cpp

@@ -1262,8 +1262,14 @@ quic::Expected<void, QuicError> onServerReadDataFromOpen(
     }
 
     auto& ackState = getAckState(conn, packetNumberSpace);
-    uint64_t distanceFromExpectedPacketNum =
+    auto addResult =
         addPacketToAckState(conn, ackState, packetNum, readData.udpPacket);
+    if (!addResult.has_value()) {
+      return quic::make_unexpected(QuicError(
+          TransportErrorCode::INTERNAL_ERROR,
+          "Failed to add packet to ack state"));
+    }
+    uint64_t distanceFromExpectedPacketNum = addResult.value();
     if (distanceFromExpectedPacketNum > 0) {
       QUIC_STATS(conn.statsCallback, onOutOfOrderPacketReceived);
     }