fix: reschedule when exact alarms are allowed again

Granting "Alarms & reminders" again left the next alarm on the inexact
fallback until something else re-registered it. The system's permission
broadcast now reschedules alarms and timers.

app/src/main/AndroidManifest.xml

@@ -269,6 +269,7 @@
                 <action android:name="android.intent.action.TIME_SET" />
                 <action android:name="android.intent.action.TIMEZONE_CHANGED" />
                 <action android:name="android.intent.action.MY_PACKAGE_REPLACED" />
+                <action android:name="android.app.action.SCHEDULE_EXACT_ALARM_PERMISSION_STATE_CHANGED" />
             </intent-filter>
         </receiver>