feat(menuitem): Add selected styles, adjust colors
feat(menuitem): Add selected styles, adjust colors

* Remove regular variant
* export Item type

Co-authored-by: kylegach <5808d44884677a824796217c374d2bafc105ea73@ca.com>
Co-authored-by: Victoria Vasys <ff6f8588a62f782cf9af7ecedda0669d998f68e9@gmail.com>
Co-authored-by: Mike Holm <5b8f23206366695112c9b1252fcc4a44254e31e2@rallydev.com>

mineral-ui/mineral-ui,mineral-ui/mineral-ui