Use AvailableVirtualKeyboardFragment for IME settings

CL[1] make InputMethodPreference support:
-. Tap to corresponding IMEs settings
-. Using switch to enable/disble IMEs

Using AvailableVirtualKeyboardFragment for
language and input settings entries and
remove unused files.

[1]: I445551e4112117aabd8d7a48f53c29b7ffd8bafd

Bug: 197705032
Test: Manually test settings keyboard flow, test video in bug
Change-Id: I4d74df7d2dda71661e3298c7070459885aa308cb
diff --git a/res/xml/language_and_input.xml b/res/xml/language_and_input.xml
index 642af3b..2055ab7 100644
--- a/res/xml/language_and_input.xml
+++ b/res/xml/language_and_input.xml
@@ -32,7 +32,7 @@
         <Preference
             android:key="virtual_keyboard_pref"
             android:title="@string/virtual_keyboard_category"
-            android:fragment="com.android.settings.inputmethod.VirtualKeyboardFragment"
+            android:fragment="com.android.settings.inputmethod.AvailableVirtualKeyboardFragment"
             settings:keywords="@string/keywords_virtual_keyboard"/>
         <Preference
             android:key="physical_keyboard_pref"
@@ -93,7 +93,7 @@
         <Preference
             android:key="virtual_keyboards_for_work_pref"
             android:title="@string/virtual_keyboards_for_work_title"
-            android:fragment="com.android.settings.inputmethod.VirtualKeyboardFragment"
+            android:fragment="com.android.settings.inputmethod.AvailableVirtualKeyboardFragment"
             settings:forWork="true"
             settings:controller="com.android.settings.inputmethod.VirtualKeyboardForWorkPreferenceController" />