add FOREGROUND_SERVICE for no_tun mode, not using vpn service (#1203)

1. add FOREGROUND_SERVICE related code, connection not to be **blocked by android system** when apps running in background
2. no_tun mode not enabling vpnservice, makeing other app to use vpnservice

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

easytier-gui/src-tauri/gen/android/app/src/main/AndroidManifest.xml

@@ -1,6 +1,10 @@
 <?xml version="1.0" encoding="utf-8"?>
 <manifest xmlns:android="http://schemas.android.com/apk/res/android">
     <uses-permission android:name="android.permission.INTERNET" />
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
+    <uses-permission android:name="android.permission.POST_NOTIFICATIONS" />
+    <uses-permission android:name="android.permission.FOREGROUND_SERVICE_DATA_SYNC" />
+
     <application
         android:icon="@mipmap/ic_launcher"
         android:label="@string/app_name"
@@ -18,6 +22,12 @@
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
+        <service
+            android:name=".MainForegroundService"
+            android:foregroundServiceType="dataSync"
+            android:enabled="true"
+            android:exported="false">
+        </service>
 
         <provider
           android:name="androidx.core.content.FileProvider"