[Settings] replace isNonTtyOrTtyOnVolteEnabled() in WFC

1. Code refactor
2. Replace ImsManager#isNonTtyOrTtyOnVolteEnabled() by combination of
   TelecomManager#getCurrentTtyMode() and
   ImsMmTelManager#isTtyOverVolteEnabled()

Bug: 140542283
Test: manual
Change-Id: Ia5179ee1a23f054899bc74c796542bae40cdc8d5

src/com/android/settings/network/ims/ImsQueryTtyOnVolteStat.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.settings.network.ims;
+
+import android.telephony.ims.ImsMmTelManager;
+
+
+/**
+ * An {@code ImsQuery} for accessing IMS tty on VoLte stat
+ */
+public class ImsQueryTtyOnVolteStat extends ImsDirectQueryImpl {
+
+    /**
+     * Constructor
+     * @param subId subscription id
+     */
+    public ImsQueryTtyOnVolteStat(int subId) {
+        mSubId = subId;
+    }
+
+    private volatile int mSubId;
+
+    /**
+     * Query running within a {@code Callable}
+     *
+     * @return result of query
+     */
+    public Boolean call() {
+        final ImsMmTelManager imsMmTelManager = ImsMmTelManager.createForSubscriptionId(mSubId);
+        return imsMmTelManager.isTtyOverVolteEnabled();
+    }
+}