Add autoclick shortcut to search index when
enable_autoclick_indicator flag is enabled.
Hide it when the flag is off.
Bug: 397719419
Test: atest ToggleAutoclickPreferenceFragmentTest
Flag: com.android.server.accessibility.enable_autoclick_indicator
Change-Id: Ib6d25067d024ff0dbea64d17d38fc544c615db97