* Remove customized (unmaintained) dropdown, improve aria a11y for dropdown
* fix repo permission
* use action instead of onChange
* re-order the CSS selector
* fix dropdown behavior for repo permissions, make elements inside menu item non-focusable
* use menu/menuitem instead of combobox/option. use tooltip(data-content) for aria-label, prevent from repeated attaching
* click menu item when pressing Enter
* code format
* fix repo permission
* repo setting: prevent from misleading users when error occurs
* fine tune the repo collaboration access mode dropdown (in case the access mode is undefined in the template)
Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>
wxiaoguang