Ensure access to mobile network configs is restricted.

This CL check if access to mobile network configurations are restricted before initializing and enabling CallFeaturesSetting, PhoneAccountSettingsActivity, and VoicemailSettingsActivity. This reolves a security vulnerability where users were able to configure the various  mobile network settings (Call, voicemail, phone accounts, FDN, etc.) even after the device owner had applied the no_config_mobile_networks restriction.

Fixes: 277589443
Test: Manual using the POC apks
Flag: com.android.internal.telephony.flags.ensure_access_to_call_settings_is_restricted
Change-Id: Id288879bfe9384472e3701e455c5ed607430a967
diff --git a/AndroidManifest.xml b/AndroidManifest.xml
index 97f5858..09258a4 100644
--- a/AndroidManifest.xml
+++ b/AndroidManifest.xml
@@ -271,7 +271,7 @@
 
         <activity android:name="GsmUmtsCallOptions"
                 android:label="@string/gsm_umts_options"
-                android:exported="true"
+                android:exported="false"
                 android:theme="@style/DialerSettingsLight">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
@@ -280,7 +280,7 @@
 
         <activity android:name="CdmaCallOptions"
                 android:label="@string/cdma_options"
-                android:exported="true"
+                android:exported="false"
                 android:theme="@style/DialerSettingsLight">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
@@ -330,7 +330,7 @@
         <!-- fdn setting -->
         <activity android:name="com.android.phone.settings.fdn.FdnSetting"
                 android:label="@string/fdn"
-                android:exported="true"
+                android:exported="false"
                 android:theme="@style/CallSettingsWithoutDividerTheme">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />