Add mod_audio_fork to FreeSWITCH's build alongside libwebsockets
(which mod_audio_fork depends on).
mod_audio_fork is used by the built in transcription feature as
a way to extract L16 streams from FreeSWITCH via WebSockets for further
processing by arbitrary transcription servers.
For full details on mod_audio_fork itself, please check drachtio's
source repo: github.com/drachtio/drachtio-freeswitch-modules.git
A few cautionary tales about this one:
- The new patch (mod_audio_fork_build.patch) guarantees libwebsockets
is properly linked to FreeSWITCH and that mod_audio_fork is built as
well. That's because mod_audio_fork is not an upstream module.
- The patch _may_ introduce conflicts on FreeSWITCH bumps more easily
than the other patches we have. They shouldn't be too hard to adapt,
though.
- There's fine tuning to be done to FreeSWITCH's unit file regarding
mod_audio_fork's capabilities. Again: check drachtio's repo.
