Consolidate keyIcon and code with keyLabel attribute

java/res/values/attrs.xml

java/res/xml-sw600dp/key_styles_common.xml

java/res/xml-sw600dp/key_styles_enter.xml

java/res/xml/key_devanagari_sign_anusvara.xml

java/res/xml/key_devanagari_sign_candrabindu.xml

java/res/xml/key_devanagari_sign_nukta.xml

java/res/xml/key_devanagari_vowel_sign_candra_o.xml

java/res/xml/key_devanagari_vowel_sign_vocalic_r.xml

java/res/xml/key_styles_common.xml

java/res/xml/key_styles_enter.xml

java/res/xml/key_styles_number.xml

java/res/xml/keys_curly_brackets.xml

java/res/xml/keys_less_greater.xml

java/res/xml/keys_parentheses.xml

java/res/xml/keys_square_brackets.xml

java/res/xml/keystyle_devanagari_sign_virama.xml

java/res/xml/keystyle_devanagari_sign_visarga.xml

java/res/xml/keystyle_devanagari_vowel_sign_aa.xml

java/res/xml/keystyle_devanagari_vowel_sign_ai.xml

java/res/xml/keystyle_devanagari_vowel_sign_au.xml