Make some symbols internal/private

[MGaetan89]

Pull request

Description

This PR changes the visibility of some symbols in pillarbox-player so they are not exposed unnecessarily to integrators.
This will also help limit the amount of data that we show to integrators in the documentation.

Changes made

• Make PillarboxBuilder.create() internal: this method creates a PillarboxExoPlayer, whose constructor is already internal. Everything needed by this method can be customized via methods on PillarboxBuilder.
• Make PillarboxAnalyticsListener and PlaybackSessionManager.Listener implementations inner classes in MetricsCollector: there's no need to expose these, since they are only needed inside of MetricsCollector.
• Make List<TimeRange>.firstOrNullAtPosition(position: Long) internal: seems rather specific to our needs. But I'm open to reverting this.
• Make MonitoringConfigFactory's constructor internal: it is only necessary inside PillarboxBuilder to create the DSL structure.

Open points

There are other symbols that may be removed/internalized. Tell me what you think about them:

• Format.selectionString(): seems more like a debug method. I think we can remove it.
• Format.roleString(): same as above.
• BitrateUtil: only used in the demo. I suggest moving it there.
• StringUtil: seems more like a debug class. Maybe we can internalize it or remove it.
• [pillarbox-ui] KeepScreenOn: only used in the demo. What about moving it there?

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).

[github-actions]

Code Coverage

Overall Project	47.91% -0.69%	🟢
Files changed	59.16%	🟢

Module	Coverage
:pillarbox-player	55.59% -1.36%	🟢

Files

Module	File	Coverage
:pillarbox-player	PillarboxBuilder.kt	78.07%	🟢
	MetricsCollector.kt	66.23% -31.13%	🟢
	MonitoringMessageHandler.kt	3.55% -1.02%	🟢