17465 Fixed dropdown cursor key navigation ## What does this MR do? This MR fixes the use of cursor/arrow/enter key events with search dropdowns, allowing a user to navigate up and down the list with the arrow keys and then select their item with the enter key. It also applies some *minor* scroll user experience fixes, such as resetting the selected dropdown item every time it opens/closes (also stops multiple dropdowns conflicting) and forcing the dropdown scroll to scroll right to the top or bottom depending on whether they have selected the first or last item, respectively. ## Are there points in the code the reviewer needs to double check? I would like someone with GitLab experience to check over whether this would harm any unique implementations of the GitLabDropdown or SearchAutocomplete. ## Why was this MR needed? The current version has incorrectly behaving search dropdowns in the navbar, they either do not navigate using the keyboard or do not use the enter keystroke to select a highlighted item. ## What are the relevant issue numbers? Fixes #17465. Closes #20752. Closes #21014. **Contributes** to #20754. ## Screenshots (if relevant)  See merge request !4781
Updated spec HAML
Added bootstrap dropdown event triggers to invoke the open and close methods of the dropdown, allowing for the binding of array key events Added #17465 fix entry to CHANGELOG Fixed multi-dropdown selected row index conflict Fixed whitespace diff Added padding to the dropdown content iterative scroll as well as new conditional scrolls to scroll all the way to the top when the first item of a list is selected and to scroll all the way to the bottom when the last item of a list is selected Added conditionals to the enable and disable autocomplete methods to stop multiple invocations without any enabled/disabled state change Fixes some incorrect firing of requests. The dropdown box was invoking a new query every time it closed and the GitLabDropdownRemote callback was invoking a new query which was causing the dropdown double render issue. Added .selectable css class to dropdown list items that are not dividers or headers and altered selectors to account for that. Moved scroll padding Number to variable. Removed unused method Started Dropdown tests Added fixture and began first test Almost finished, navigation done, action and close needed YAY. TESTS DONE. Altered test and fixed click started removing selectable class use Fixed as reviewed altered selection method Fixed autocomplete shutting dropdown on arrow key use patched XSS vulns updated tests f Added click fixes