Expanded LauncherPrefs APIs to Replace Direct Shared Preference Usage.

LauncherPrefs will contain Launcher's shared preference functionality.
It controls optimizations and classifications such as restorable vs
non-restorable data, bootaware vs non-bootaware data, and configurations
such as default values  so the calling code doesn't need to and our code
base can have a single source of truth for items that are used in
multiple places.

The old APIs remain in place, but are deprecated and will be removed
after all Shared Preference usage has been gated by LauncherPrefs in
future CLs.

Bug: 261635315
Test: Manually tested themed icon, Workspace configuration, and app
install functionality.

Change-Id: I29fd516468bc93fda393062e95be26b6d55c816e