Provide ability for admins to manage user organisation membership & admin rights

- Required overwriting a bunch of base code to slot in the handling
- Admins are shown with yellow text in their organisation label

src/Database/Models/Organisation.php

@@ -254,4 +254,20 @@ class Organisation extends Model implements OrganisationInterface
                 $join->on('admin_counts.organisation_id', '=', 'organisations.id');
             });
     }
+
+    /**
+     * Query scope to get all organisations a specific user is a member of.
+     *
+     * @param Builder $query
+     * @param int     $userId
+     *
+     * @return Builder
+     */
+    public function scopeForUser($query, $userId)
+    {
+        return $query->join('organisation_members', function ($join) use ($userId) {
+            $join->on('organisation_members.organisation_id', 'organisations.id')
+                 ->where('user_id', $userId);
+        });
+    }
 }