Methods to streamline bulk media operations.

The new storage model being built in Android Q and R means that most
apps will now be limited to read access to most media items on the
device.  This change adds a way for developers to request a user to
grant narrow access to specific media items.

This supports operations like requesting write access, trash/untrash,
favorite/unfavorite, and outright delete.  Once the user confirms the
action in the dialog, the action is carried out with no further
action needed by the caller.

We transport the set of Uris through a ClipData to pave the way for
shifting to ParceledListSlice in a future release.

Since there's many permutations of strings needed, generate them
with a simple Python script to ensure they stay consistent.

Bug: 141911164
Test: atest --test-mapping packages/apps/MediaProvider
Test: atest CtsAppSecurityHostTestCases:android.appsecurity.cts.ExternalStorageHostTest#testMediaEscalation
Change-Id: I2eb3775550ed27c2863af1edc362471e4cb48643