Add device volume management to PillarboxCastPlayer

[MGaetan89]

Description

This PR implements the following method in PillarboxCastPlayer:

• handleSetDeviceVolume().
• handleIncreaseDeviceVolume().
• handleDecreaseDeviceVolume().
• handleSetDeviceMuted().

These implementations are based on AndroidX Media3's implementations from androidx/media@405365c.

Changes made

• Use the CastSession to handle to device volume instead of the RemoteMediaClient.
• Implement device-related volume management methods.
• Move the MediaRouteSelector to the ViewModel and use the one provided by Cast if available.

Checklist

• APIs have been properly documented (if relevant).
• The documentation has been updated (if relevant).
• New unit tests have been written (if relevant).
• The demo has been updated (if relevant).

[MGaetan89]

This is not yet in the released version of Media3. You can see the explanation here for now:
https://github.com/androidx/media/blob/bd24ec08d13d74f2aae417b85f4cb40092c13f7e/libraries/cast/src/main/java/androidx/media3/cast/CastPlayer.java#L100-L107

[github-actions]

Code Coverage

Overall Project	49.17% -0.58%	🟢
Files changed	13.16%	🟢

Module	Coverage
:pillarbox-player	57.61%	🟢
:pillarbox-cast	18.81% -6.29%	🟢

Files

Module	File	Coverage
:pillarbox-player	StringUtil.kt	100%	🟢
:pillarbox-cast	RemoteMediaClient.kt	87.42%	🟢
	PillarboxCastPlayer.kt	1.14% -10.72%	🟢