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/state/QuicStateFunctions.cpp

@@ -395,7 +395,7 @@ uint64_t maximumConnectionIdsToIssue(const QuicConnectionStateBase& conn) {
   return maximumIdsToIssue;
 }
 
-uint64_t addPacketToAckState(
+Expected<uint64_t, IntervalSetError> addPacketToAckState(
     QuicConnectionStateBase& conn,
     AckState& ackState,
     const PacketNum packetNum,
@@ -407,7 +407,10 @@ uint64_t addPacketToAckState(
   ackState.largestRecvdPacketNum = std::max<PacketNum>(
       ackState.largestRecvdPacketNum.value_or(packetNum), packetNum);
   auto preInsertVersion = ackState.acks.insertVersion();
-  ackState.acks.insert(packetNum);
+  auto insertResult = ackState.acks.tryInsert(packetNum);
+  if (!insertResult.has_value()) {
+    return quic::make_unexpected(insertResult.error());
+  }
   if (preInsertVersion == ackState.acks.insertVersion()) {
     QUIC_STATS(conn.statsCallback, onDuplicatedPacketReceived);
   }
@@ -446,7 +449,7 @@ uint64_t addPacketToAckState(
     return (packetNum > expectedNextPacket) ? packetNum - expectedNextPacket
                                             : expectedNextPacket - packetNum;
   } else {
-    return 0;
+    return uint64_t{0};
   }
 }