Copy LocationProviderBase API into SystemApi surface

This allows third party location providers to link against the standard
API surface. This replaces the LocationProviderBase implementation in
the com.android.location.providers API. Both will temporarily coexist
until third party applications can be migrated, and then old version
will be removed. Only the LocationProviderBase API is migrated right now
as its the only API that has undergone changes.

This also restores some old, unused classes which should not have been
remove from the API surface. Clients that support older API version will
still need to link against these classes.

Bug: 176115245
Test: builds
Change-Id: I2d688447e1f59e441f5c48ff36d3f0dd8b5dc7f6