Fix SDK annotations in AppPermissionViewModel

showMediaConfirmDialog() should be annotated with @RequiresApi instead
of @ChecksSdkIntAtLeast. It's not checking SDK int internally, and
requires the caller to check it.

expandsToStorageSupergroup() can be annotated with @ChecksSdkIntAtLeast
because Utils.STORAGE_SUPERGROUP_PERMISSIONS is only non-empty on T+.

Fix: 234775341
Test: presubmit
Change-Id: I04c2ee59b7e8519e8733ae9103234ab146295829