MediaSession: update metadata @ every heartbeat

[rtshkmr]

Present Context

Currently the media sessions meta update has only been updated @ the time of load of the audio, and only play pause action handlers have been wired up.

We might want to wire up the other action handlers or functions like setPlaybackPosition that might improve the experience.

e.g. of other event handlers for scribing / seekTo / fastSeek
So that the media session API, which can already be used to do those operations on the playback, will be synced to states that we are managing on our live components.

however, this is low priority because it's only an incremental improvement from before.