Add data when member joined a team

CHANGELOG

@@ -47,6 +47,7 @@ v 8.10.0 (unreleased)
   - Handle custom Git hook result in GitLab UI
   - Allow '?', or '&' for label names
   - Fix importer for GitHub Pull Requests when a branch was reused across Pull Requests
+  - Add date when user joined the team on the member page
 
 v 8.9.5
   - Add more debug info to import/export and memory killer. !5108

app/views/shared/members/_member.html.haml

@@ -21,6 +21,10 @@
         %span.cgray
           – Requested
           = time_ago_with_tooltip(member.requested_at)
+      - else
+        %span.cgray
+          = "(joined #{time_ago_with_tooltip(member.created_at)})"
+
     - else
       = image_tag avatar_icon(member.invite_email, 24), class: "avatar s24", alt: ''
       %strong= member.invite_email