Enforce MANAGE_APP_PREDICTIONS on hasShareTargets

ShortcutManager#hasShareTargets() is used in ShareSheet, which is moving
out of system process. So we need to annotate hasShareTargets as systemApi
and enforce permission on the caller.

Bug: 123779604
Test: atest ShortcutManagerTest1
Change-Id: Ib2352f0e8600b0e792405af5b9b61b380c050d28