[ML1] Introduce RichInputMethodSubtype

...thod/accessibility/MainKeyboardAccessibilityDelegate.java

...oid/inputmethod/compat/InputMethodSubtypeCompatUtils.java

java/src/com/android/inputmethod/keyboard/KeyboardId.java

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

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

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

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

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

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

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

...utmethod/latin/spellcheck/AndroidSpellCheckerService.java

...s/DistracterFilterCheckingExactMatchesAndSuggestions.java

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

...roid/inputmethod/keyboard/KeyboardLayoutSetTestsBase.java

...thod/keyboard/internal/LanguageOnSpacebarHelperTests.java

...d/inputmethod/latin/utils/SpacebarLanguageUtilsTests.java

...roid/inputmethod/latin/utils/SubtypeLocaleUtilsTests.java