FS-7519 FS-7517: looks like decoders don't decode FU-A bit steams, this is a simple implementation that works with some FU-A bit streams, mod_av works better most cases

FS-7500: factor out the write_image callback and fix the vlc video endpoint to setup and match the audio params of the A leg when bridged

FS-7500: reduce CNG frames on video and move debug from mod_fsv to the core with a flag to enable it since the raw packet is not available anymore when you set DECODED READ flag

FS-7500: reverse default for CF_VIDEO_ECHO to false and now it must be enabled when desired instead of disabled when not needed

FS-7500: add switch_core_session_raw_read to put session into raw read mode without needing a local codec var (WE SHOULD REFACTOR MUCH OF switch_ivr_* to use this...) and add echo_decode_audio option to echo app

FS-7508: change vpx encoder to not re-init the whole codec, it messes it up but side effect, we need to init the encoder at 4k and scale down to aovid the vpx resize seg