Add debug settings for keypress popup animations

java/res/values/attrs.xml

java/res/values/config-common.xml

java/res/values/strings.xml

java/res/values/themes-common.xml

java/res/xml/prefs_for_debug.xml

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

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

...nputmethod/keyboard/internal/KeyPreviewChoreographer.java

...d/inputmethod/keyboard/internal/KeyPreviewDrawParams.java

...com/android/inputmethod/latin/settings/DebugSettings.java

.../src/com/android/inputmethod/latin/settings/Settings.java

...om/android/inputmethod/latin/settings/SettingsValues.java

...rc/com/android/inputmethod/latin/utils/ResourceUtils.java