dcsctp: Limit the effect of state cookie tampering

This commit enhances the security and robustness of the state cookie by
limiting what an attacker can achieve even if they manage to forge or
tamper with the cookie.

By storing the raw peer capabilities in the state cookie, we prevent an
attacker from enabling extensions that the local socket didn't signal
support for, limit the stream limits (incoming and outgoing) from what
was originally announced, and also eliminate some duplication in
capability parsing in the different methods to do connection handshakes.

This ensures that the state instantiated from a COOKIE ECHO strictly
matches the parameters of the original INIT, and if an attacker tampers
with it, the effects are very limited.

Bug: webrtc:522976080
Change-Id: Ia038ce183cbc28301d26be4a5657c6867dbff306
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/488460
Commit-Queue: Victor Boivie <boivie@webrtc.org>
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#48182}