When apn is read only, hide the save button.

Test: Visual Test
Fix: 320200491
Change-Id: I8280fdaa3643a982137936473d827b8502a6e023

src/com/android/settings/network/apn/ApnEditPageProvider.kt

@@ -101,6 +101,7 @@ fun ApnPage(apnDataInit: ApnData, apnDataCur: MutableState<ApnData>, uriInit: Ur
     RegularScaffold(
         title = if (apnDataInit.newApn) stringResource(id = R.string.apn_add) else stringResource(id = R.string.apn_edit),
         actions = {
+            if (!apnData.customizedConfig.readOnlyApn) {
                 IconButton(onClick = {
                     if (!apnData.validEnabled) apnData = apnData.copy(validEnabled = true)
                     val valid = validateAndSaveApnData(
@@ -112,6 +113,7 @@ fun ApnPage(apnDataInit: ApnData, apnDataCur: MutableState<ApnData>, uriInit: Ur
                     )
                     if (valid) navController.navigateBack()
                 }) { Icon(imageVector = Icons.Outlined.Done, contentDescription = null) }
+            }
         },
     ) {
         Column {
@@ -212,7 +214,9 @@ fun ApnPage(apnDataInit: ApnData, apnDataCur: MutableState<ApnData>, uriInit: Ur
                 emptyVal = stringResource(R.string.network_type_unspecified),
                 enabled = apnData.networkTypeEnabled
             ) {}
-            if (!apnData.newApn) {
+            if (!apnData.newApn && !apnData.customizedConfig.readOnlyApn
+                && apnData.customizedConfig.isAddApnAllowed
+            ) {
                 Preference(
                     object : PreferenceModel {
                         override val title = stringResource(R.string.menu_delete)