Fix: add avatar for UI (#11080)

### What problem does this PR solve?

Add avatar for admin UI.

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

admin/server/services.py

@@ -52,6 +52,7 @@ class UserMgr:
         result = []
         for user in users:
             result.append({
+                'avatar': user.avatar,
                 'email': user.email,
                 'language': user.language,
                 'last_login_time': user.last_login_time,
@@ -170,7 +171,8 @@ class UserServiceMgr:
         return [{
             'title': r['title'],
             'permission': r['permission'],
-            'canvas_category': r['canvas_category'].split('_')[0]
+            'canvas_category': r['canvas_category'].split('_')[0],
+            'avatar': r['avatar']
         } for r in res]