A11yManagerService turns off button targets for services whose packages have forcibly stopped.

Change involves reorganizing relevant code so that it is testable.
Exposed code is documented.

Feature flag:
-namespace: accessibility
-flag: com.android.server.accessibility.disable_continuous_shortcut_on_force_stop

Bug: 198018180
Test: atest A11yManagerServiceTest
Change-Id: Ic54591590af402115607f2d0f524276d1ec365f7
diff --git a/services/accessibility/accessibility.aconfig b/services/accessibility/accessibility.aconfig
index f09cb19..1a735f8 100644
--- a/services/accessibility/accessibility.aconfig
+++ b/services/accessibility/accessibility.aconfig
@@ -43,6 +43,13 @@
 }
 
 flag {
+    name: "disable_continuous_shortcut_on_force_stop"
+    namespace: "accessibility"
+    description: "When a package is force stopped, remove the button shortcuts of any continuously-running shortcuts."
+    bug: "198018180"
+}
+
+flag {
     name: "deprecate_package_list_observer"
     namespace: "accessibility"
     description: "Stops using the deprecated PackageListObserver."