Bus player for MPF 0.80 (replaces Track player from MPF 0.57)

[avanwinkle]

This PR introduces support for bus_player commands from MPF, akin to the track_player configs of MPF 0.57. The GMC companion PR is at missionpinball/mpf-gmc#8

Three actions are supported: pause, unpause, and stop.

bus_player:
  delay_pause:
    music:
      action: pause
      fade: 2s
  delay_resume:
    music:
      action: unpause
      fade: 2s
  delay_stop:
    music:
      action: stop
      fade: 1s

Note that when a bus pauses, the channel is no longer considered active and may be replaced by a new sound request. To ensure proper isolation of sound files on a bus, use a unique bus for those sounds.

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud