Force PulseAudio sample format if the source format is not supported by OBS

If the sample format used by PulseAudio can not be converted into an
OBS audio format it will be handled as AUDIO_FORMAT_UNKNOWN which will
not result in a proper audio recording. So instead we request a format
that OBS supports from PulseAudio and let it do the format conversion.
Merge branch 'opengl_screen_tearing_workaround' into HEAD
Merge branch 'fix_creating_flipped_textures' into HEAD
Merge branch 'fix_shutdown_crash_on_plugin_unloading' into HEAD
Merge branch 'fix_pulse_audio_format_conversion' into HEAD
Merge remote-tracking branch 'btbn/pa_app_capture' into HEAD