Support bearer token authentication

[neilyoung]

Describe the feature

Description

I hope it's not again an RTMF issue and it's all long time realised and documented, but at the moment it seems to me that MediaMTX supports BASIC and DIGEST authentication only for WebRTC WHIP/WHEP. IMHO the RFC mandates bearer token authentication, so it would be great, if that could be supported.

[kaitlynia]

Not only is this mandated by RFC, but OBS supports this in the UI for WHIP and it was a source of confusion for me when I assumed this was the method that MediaMTX handled JWT-based auth, but was disappointed to find out that it's just more URL-parameterized auth.