Support more keys accessibility mode

java/res/values/config-common.xml

java/res/values/strings-talkback-descriptions.xml

...nputmethod/accessibility/AccessibilityLongPressTimer.java

...utmethod/accessibility/KeyboardAccessibilityDelegate.java

...thod/accessibility/MainKeyboardAccessibilityDelegate.java

.../accessibility/MoreKeysKeyboardAccessibilityDelegate.java

...om/android/inputmethod/keyboard/MoreKeysKeyboardView.java

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

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