Add Quick Settings tile (#660)

* Add Quick Settings tile

- Add multi-client support to AmneziaVpnService
- Make AmneziaActivity permanently connected to AmneziaVpnService while it is running
- Refactor processing of connection state changes on qt side
- Add VpnState DataStore
- Add check if AmneziaVpnService is running

* Add tile reset when the server is removed from the application

client/android/AndroidManifest.xml

@@ -56,6 +56,10 @@
                 <category android:name="android.intent.category.DEFAULT" />
             </intent-filter>
 
+            <intent-filter>
+                <action android:name="android.service.quicksettings.action.QS_TILE_PREFERENCES" />
+            </intent-filter>
+
             <meta-data
                 android:name="android.app.lib_name"
                 android:value="-- %%INSERT_APP_LIB_NAME%% --" />
@@ -146,6 +150,22 @@
             </intent-filter>
         </service>
 
+        <service
+            android:name=".AmneziaTileService"
+            android:process=":amneziaTileService"
+            android:icon="@drawable/ic_amnezia_round"
+            android:permission="android.permission.BIND_QUICK_SETTINGS_TILE"
+            android:exported="true">
+
+            <intent-filter>
+                <action android:name="android.service.quicksettings.action.QS_TILE" />
+            </intent-filter>
+
+            <meta-data
+                android:name="android.service.quicksettings.TOGGLEABLE_TILE"
+                android:value="true" />
+        </service>
+
         <provider
             android:name="androidx.core.content.FileProvider"
             android:authorities="org.amnezia.vpn.qtprovider"