Add rememberPlayer(THEOplayerView)

[MattiasBuelens]

Currently, the UI always creates its own THEOplayerView:

• If you call DefaultUI with a config parameter, then it creates a THEOplayerView and Player itself.
• If you call DefaultUI with a player parameter, you still have to create that Player using rememberPlayer(), which always creates a THEOplayerView itself.

This adds a new overload rememberPlayer(THEOplayerView), which wraps an existing THEOplayerView in a Player rather than creating a new one. This makes it easier to add integrations upfront, or to remove the UI without removing the player.