Change resolution mechanism for setPermittedInputMethosd to SetIntersection

Instead of applying the most recent settings that might be wrong if two
or more admins try to set it, we now return a minimum set - methods that
are allowed by all admins.

Bug: 340914586
Flag: android.app.admin.flags.use_policy_intersection_for_permitted_input_methods
Change-Id: I1778bb8c0c4df42f1447ec739b4ffaee82f8da5a