Apply GitLab UI button styles to buttons in app/views/shared/issuable directory

Instructions

For instructions about how to apply GitLab UI button styles to the button instances on these templates, see the epic &4001 (closed).

Files in directory with buttons that needs migration

• app/views/shared/issuable/_board_create_list_dropdown.html.haml
• app/views/shared/issuable/_bulk_update_sidebar.html.haml
• app/views/shared/issuable/_close_reopen_button.html.haml
• app/views/shared/issuable/_close_reopen_report_toggle.html.haml
• app/views/shared/issuable/_feed_buttons.html.haml
• app/views/shared/issuable/_form.html.haml
• app/views/shared/issuable/_label_page_create.html.haml
• app/views/shared/issuable/_search_bar.html.haml
• app/views/shared/issuable/_sidebar.html.haml
• app/views/shared/issuable/_sort_dropdown.html.haml
• app/views/shared/issuable/_user_dropdown_item.html.haml