Unify automatic storage management enabled checks.

By putting it in SettingsLib, it should be accessible to every app that
needs it.

This also adds in the ability for the framework to define default
behavior. The default behavior for the storage manager enabled status
may differ based upon the device.

Bug: 70893105
Test: SettingsLib Robotests
Change-Id: I9082a77f90289b8fa208c628dd3606000e19495b