Update codec parameters from first keyframe

[seydx]

Dynamically extracts and updates codec parameters (SPS/PPS for H.264, VPS/SPS/PPS for H.265) from the first keyframe when they are missing or incomplete in the initial stream setup.

Problem

Some RTSP cameras don't send parameter sets in the DESCRIBE response, resulting in missing or incorrect codec FmtpLine. This causes issues with MSE playback (incorrect aspect ratios) and other consumers that rely on accurate codec information.

Solution

• Extract parameter sets from the first keyframe with complete data
• Update codec.FmtpLine dynamically in format handlers (RepairAVCC, RTPDepay)
• Apply handlers in probe consumer for universal coverage

Note: The FmtpLine update happens during processing of the first keyframe, so it does not affect the first consumer but benefits all subsequent consumers. This makes it ideal for use with preload - the preloader processes the first keyframe and updates the codec parameters, then all following consumers receive the correct FmtpLine.

Fixes #1634