Enhance ImfUtils to InputMethodManagerWrapper class

...d/inputmethod/compat/InputMethodManagerCompatWrapper.java

...rc/com/android/inputmethod/keyboard/KeyboardSwitcher.java

.../android/inputmethod/latin/AdditionalSubtypeSettings.java

java/src/com/android/inputmethod/latin/LatinIME.java

...com/android/inputmethod/latin/RichInputMethodManager.java

java/src/com/android/inputmethod/latin/SettingsValues.java

java/src/com/android/inputmethod/latin/SubtypeSwitcher.java

...c/com/android/inputmethod/keyboard/SpacebarTextTests.java

...src/com/android/inputmethod/latin/SubtypeLocaleTests.java