Add a RTT setting in A11y screen

- Add RTT setting in Accessibility screen.
- Create a controller for RTT setting preference.
- Create an array strings to define the subtext.

Test: Rebuild, and visual
Change-Id: I248654c822284473b8a8265de4a3938af89cdf7a
Merged-In: I248654c822284473b8a8265de4a3938af89cdf7a
Fix: 146540478

res/values/arrays.xml

@@ -1419,4 +1419,16 @@
         <item>@string/enhanced_4g_lte_mode_summary_4g_calling</item>
     </string-array>
 
+    <!--String arrays for showing the rtt settings options -->
+    <string-array name="rtt_setting_mode">
+        <!-- 0: Invalid value -->
+        <item></item>
+        <!-- 1:  Not visible -->
+        <item>@string/rtt_settings_no_visible</item>
+        <!-- 2:  Visible during call -->
+        <item>@string/rtt_settings_visible_during_call</item>
+        <!-- 3:  Always visible -->
+        <item>@string/rtt_settings_always_visible</item>
+    </string-array>
+
 </resources>

res/values/config.xml

@@ -420,4 +420,8 @@
 
     <!-- RTT setting intent action -->
     <string name="config_rtt_setting_intent_action" translatable="false"></string>
+
+    <!-- Package name of dialer supports RTT setting-->
+    <string name="config_rtt_setting_package_name" translatable="false"></string>
+
 </resources>