Add subtext for default keyboard layout.

        e.g. English (US) - X Keyboard -->

    <string name="physical_device_title"><xliff:g id="input_method_subtype" example="English (US)">%1$s</xliff:g> - <xliff:g id="input_method_editor" example="X Keyboard">%2$s</xliff:g></string>

    <!-- Summary text for keyboards when no layout has been selected. [CHAR LIMIT=35] -->

    <string name="default_keyboard_layout">Default</string>

    <!-- On Languages & input settings screen, heading. Inside the "Languages & input settings" screen, this is the header for settings that relate to mouse and trackpad devices. [CHAR LIMIT=40] -->

    <string name="pointer_settings_category">Mouse/trackpad</string>

    <!-- On Languages & input settings screen, setting summary.  Setting for mouse pointer speed. [CHAR LIMIT=35] -->

                    KeyboardLayout layout = info.mLayout;

                    if (layout != null) {

                        pref.setSummary(layout.getLabel());

                    } else {

                        pref.setSummary(

                                getPrefContext().getString(R.string.default_keyboard_layout));

                    }

                    pref.setOnPreferenceClickListener(preference -> {

                        showKeyboardLayoutScreen(