Settings(wifi): Allow mainline wifi stack to use network request dialog

The wifi stack may not be running in system_server, so cannot get
NETWORK_SETTINGS permisison (platform signature). Guard it using the new
wifi mainline permission. If the wifi stack is running in system_server
(until it becomes a mainline module), it's uid (SYTEM_UID) should bypass all
permission checks.

Bug: 113174748
Test: Verified with CtsVerifier tests.
Change-Id: I87be97bb6e42c055d3aaa317a096256fd66f9e14
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index 3101e9a..be3983c 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -2731,7 +2731,7 @@
             android:launchMode="singleTop"
             android:taskAffinity=".wifi.NetworkRequestDialogActivity"
             android:exported="true"
-            android:permission="android.permission.NETWORK_SETTINGS">
+            android:permission="android.permission.MAINLINE_WIFI_STACK">
             <intent-filter>
                 <action android:name="com.android.settings.wifi.action.NETWORK_REQUEST" />
                 <category android:name="android.intent.category.DEFAULT" />