What's Changed in v3.12.0

Cleaned up the startup logic to ensure things start quickly and moved configurations around so everything is overrideable

• Moved API-driven snapshots into the Stream_Manager.py so they don't delay startup.
• Clean up the /var/log directory in Dockerfile build image
• Better to supply empty, not samples in config
• Switch to run for diagnostic dump
• Deprecate the config.yml setting of environment variables so we can set the IMG_DIR and RECORD_PATH reliably even
  if not running inside Home Assistant as an add-on
• Remove the MTX_* variables from the .env as we want them to be settable in the options.
• Explicitly default the MTX settings that used to be forced (MTX_READTIMEOUT=30s, MTX_HLSVARIANT=mpegts, MTX_WRITEQUEUESIZE=2048)
  to ensure backward compatibility
• Updated the defaults for the IMG_DIR and RECORD_PATH to match what the .env would have
  previously set, but now it's overridable.
• Reduced log spam by making some .info( calls .debug(
• Don't emit ffmpeg non-error messages (let the Popen eat them).

Full Changelog: v3.11.1...v3.12.0