Refactor RTP header extension ID allocation to be persistent and shared.

- Introduced RtpHeaderExtensionRecorder and RtpHeaderExtensionPicker in
call/payload_type_picker.
- Added SuggestRtpHeaderExtensionId and AddRtpHeaderExtensionMapping to
PayloadTypeSuggester interface.
- Implemented persistent RTP header extension ID mapping in
SdpPayloadTypeSuggester.
- Refactored pc/media_session.cc to use PayloadTypeSuggester for all
RTP header extension ID allocations, replacing UsedRtpHeaderExtensionIds.
- Ensured shared mapping between local and remote extensions for the
same transport.
- Maintained RFC 8285 compliance for one-byte and two-byte ID allocation.
- Updated tests to explicitly allow mixed extensions when two-byte IDs
are expected.
- Removed obsolete UsedRtpHeaderExtensionIds and its unit test.

Bug: webrtc:503013383
Change-Id: Ic98522b1eec52c736a73bd034493f19ac6524b5a
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/465300
Auto-Submit: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Reviewed-by: Tomas Gunnarsson <tommi@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#47492}