Allow cross user usage event queries

For multipackage requests, caller must be system uid or hold
interact_across_users if not requesting fate for the same user.

For single package requests, caller must be system uid or the
same package and hold interact_across_users if not requesting data
for the current user.

In both cases the caller must have the usagestats permission.

Test: couldn't find automated tests for this file; manual
Bug: 79142791
Change-Id: I8d650f8e875e0e4578cb48c9ba42e821342852a0