activity: Add a link to copy list of realm admins.

Tweaked by tabbott to do the database queries properly.

This should help user to copy realm admin emails in a go.
Fixes: #7885

zproject/settings.py

@@ -818,7 +818,10 @@ PIPELINE = {
         # If you add a style here, please update stylesheets()
         # in frontend_tests/zjsunit/output.js as needed.
         'activity': {
-            'source_filenames': ('styles/activity.css',),
+            'source_filenames': (
+                'styles/activity.css',
+                'third/thirdparty-fonts.css',
+            ),
             'output_filename': 'min/activity.css'
         },
         'stats': {