Adds PackageTagsMap.

The goal is to change the PackageTagsList API from hidden to system so
it can be used in getAdasAllowlist. However, the trunk stable flag
doesn't properly support converting an existing TestApi to a SystemApi.
To address this, we create PackageTagsMap and will remove the original
PackageTagsList once PackageTagsMap is fully rolled out.

Flag: android.location.flags.change_get_adas_allowlist_from_hidden_to_system
Test: Build and run the code
Bug: 362287534
Change-Id: Id1b538e07a7382329b5a9639c91ae8b413a1c40c