LatinIME: Add icons to settings items

java/res/drawable/ic_settings_advanced.xml

java/res/drawable/ic_settings_appearance.xml

java/res/drawable/ic_settings_gesture.xml

java/res/drawable/ic_settings_languages.xml

java/res/drawable/ic_settings_preferences.xml

java/res/drawable/ic_settings_privacy.xml

java/res/drawable/ic_settings_spellcheck.xml

java/res/xml/prefs.xml

.../android/inputmethod/latin/settings/SettingsFragment.java