Add RichInputMethodSubtype.getKeyboardLayoutSetName

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

...ndroid/inputmethod/keyboard/internal/KeyboardBuilder.java

...putmethod/keyboard/internal/LanguageOnSpacebarHelper.java

...com/android/inputmethod/latin/RichInputMethodSubtype.java

...m/android/inputmethod/latin/utils/SubtypeLocaleUtils.java