feat(site): display user avatar (#11893)

* add owner API to workspace and workspace build responses
* display user avatar in workspace top bar

Co-authored-by: Cian Johnston <cian@coder.com>

cli/testdata/coder_list_--output_json.golden

@@ -5,6 +5,7 @@
     "updated_at": "[timestamp]",
     "owner_id": "[first user ID]",
     "owner_name": "testuser",
+    "owner_avatar_url": "",
     "organization_id": "[first org ID]",
     "template_id": "[template ID]",
     "template_name": "test-template",
@@ -21,6 +22,7 @@
       "workspace_name": "test-workspace",
       "workspace_owner_id": "[first user ID]",
       "workspace_owner_name": "testuser",
+      "workspace_owner_avatar_url": "",
       "template_version_id": "[version ID]",
       "template_version_name": "[version name]",
       "build_number": 1,