Media_player.mpd: support for snapshot/restore

Home Assistant release (hass --version):
0.51.2

Component/platform:
media_player.mpd

Description of problem:
When playing music via mpd and firing an automation to output something via tts to mpd the output is stopped once the tts finished playing. If I understand it correctly some other players like e.g. sonos support a snapshot/restore function which allows to snapshot the media player state, fire the tss and then restore the old state so the music would resume playing. It would be nice to have this feature for mpd as well.