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

src/com/android/settings/inputmethod/AvailableVirtualKeyboardFragment.java

@@ -105,7 +105,7 @@ public final class AvailableVirtualKeyboardFragment extends SettingsPreferenceFr
                     || permittedList.contains(imi.getPackageName())
                     || enabledImis.contains(imi);
             final InputMethodPreference pref = new InputMethodPreference(
-                    context, imi, true, isAllowedByOrganization, this);
+                    context, imi, isAllowedByOrganization, this);
             pref.setIcon(imi.loadIcon(context.getPackageManager()));
             mInputMethodPreferenceList.add(pref);
         }