Support LengthPrefixedConnectionIds in v99

This CL adds support for the invariants change from draft-22. It introduces a new parsing method QuicFramer::ParsePublicHeader which can parse both old and new formats, and uses it for v99 and also for all versions when gfe2_reloadable_flag_quic_use_parse_public_header is true.

gfe-relnote: change v99 encoding, protected by disabled v99 flag and by gfe2_reloadable_flag_quic_use_parse_public_header.
PiperOrigin-RevId: 260871822
Change-Id: I680d12141b2731401a818ed335af03e7c5365219

quic/core/quic_ietf_framer_test.cc

diff --git a/quic/core/quic_ietf_framer_test.cc b/quic/core/quic_ietf_framer_test.cc
index dbbacdd..f0872b6 100644
--- a/quic/core/quic_ietf_framer_test.cc
+++ b/quic/core/quic_ietf_framer_test.cc
@@ -102,7 +102,7 @@
 
   bool OnProtocolVersionMismatch(
       ParsedQuicVersion /*received_version*/) override {
-    return true;
+    return false;
   }
 
   bool OnUnauthenticatedPublicHeader(