Remove IncrementalStates in favor of float for progress

Removes all of the logic from PackageSetting, making it only
contain simple data fields.

Instead, the caller in PackageManagerService will invoke any
callback/listener logic after progress is committed to the
PackageSetting.

This also eliminates a background thread debounce + re-lock,
as the entire check progress + callback cycle can be done in
a single lock block now.

Bug: 204200534

Test: atest CtsInstalledLoadingProgressHostTests

Change-Id: I315d9c4300dea425973b6df602b14c6b066ab8fd