Pull request

Description

The goal of this PR is to use default task removing from Android instead of handle it inside the customs Pillarbox classes.

Integrators have to update the service definition inside the manifest with android:stopWithTask="true"

Changes made

• Add showcase that use a MediaSessionService.
• Remove onTaskRemoved that can be configured inside the manifest.

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).