Allows for better loudness normalization vs straight volume adjustment
using the ffmpeg loudnorm filter. The i, lra, and tp values are all
configurable in the advanced transcode settings.
This adds the notion of creating and maintaining transcode
configurations. This is a generalization of the current ffmpeg settings
flow. Users can edit various settings relating to transcoding in each
config and then assign a configuration to a channel. This allows for
more fine-grained customization of transcoding per-channel and also
allows for users to test new configurations without affecting the global
state of Tunarr.
