Unregister transport when user disables corresponding package.

Register transport when user puts package in default enable state.

This change is an extension of ag/17072365.

TransportManager#onPackageChanged is not correctly handling these 2 cases -
1. When a package is disabled by user. Meaning, the state 'COMPONENT_ENABLED_STATE_DISABLED_USER' was being ignored.
2. When a package is default-enabled. Meaning, the state 'COMPONENT_ENABLED_STATE_DEFAULT' was being ignored.

If the package in question contains backup transports, they should be registered or unregistered depending on the state.

For state 'COMPONENT_ENABLED_STATE_DEFAULT', I'm considering it as if package is enabled. The only situation where package is in disabled state in default state is when it is explicitly specified in Manifest at an application level.

Bug: 162725876, 237049952
Fixes: 162725876, 237049952
Test: 1. atest -v BackupFrameworksServicesRoboTests:TransportManagerTest
	2. Manual test on device (Oriole)
		- List transports
		- Disable package via Settings -> Apps
		- List transports and verify disabled transports are not present.
		- Enable package via Settings -> Apps
		- List transports and verify default-enabled transports are present.
		- Verify logs via logcat to ensure correct switch codepaths was taken in TransportManager

Change-Id: I1d5e9f8bf5625257bd01a910d29b4dbcb68f3ab4