feat: Make the p2p H.264 high profile stripping configurable.

[th-aslam]

Companion to jitsi/jicofo#1296, as discussed in the community thread with @jallamsetty1.

TPCUtils.mungeCodecOrder unconditionally strips the non-baseline H.264 payload types from the SDP on p2p connections (SDPUtil.stripCodec(mLine, codec, true) keeps only profile-level-id=42*). For deployments that want to negotiate Main/High profile — e.g. hardware encoders that don't advertise the baseline profiles — this hardcoded strip undoes the codec configuration client-side.

This makes it configurable:

• New per-codec setting videoQuality.h264.stripHighProfile in config.js, default true — behavior is unchanged unless a deployment opts out.
• Plumbed through STANDARD_CODEC_SETTINGS and the existing per-codec config overlay in the TPCUtils constructor, same pattern as scalabilityModeEnabled/useSimulcast.
• The VP9 profile stripping and the ULPFEC/RED stripping on p2p are untouched.
• MockPeerConnection gains codecSettings/usesCodecSelectionAPI() so mungeCodecOrder is now unit-testable; two new specs cover the default strip and the opt-out (full suite 537/537 green, tsc --noEmit and eslint clean).

[jitsi-jenkins]

Hi, thanks for your contribution!
If you haven't already done so, could you please make sure you sign our CLA (https://jitsi.org/icla for individuals and https://jitsi.org/ccla for corporations)? We would unfortunately be unable to merge your patch unless we have that piece :(.