Actions Artifacts v4 backend (#28965)

Fixes #28853 

Needs both https://gitea.com/gitea/act_runner/pulls/473 and
https://gitea.com/gitea/act_runner/pulls/471 on the runner side and
patched `actions/upload-artifact@v4` / `actions/download-artifact@v4`,
like `christopherhx/gitea-upload-artifact@v4` and
`christopherhx/gitea-download-artifact@v4`, to not return errors due to
GHES not beeing supported yet.

models/fixtures/action_run.yml

@@ -17,3 +17,22 @@
   updated: 1683636626
   need_approval: 0
   approved_by: 0
+-
+  id: 792
+  title: "update actions"
+  repo_id: 4
+  owner_id: 1
+  workflow_id: "artifact.yaml"
+  index: 188
+  trigger_user_id: 1
+  ref: "refs/heads/master"
+  commit_sha: "c2d72f548424103f01ee1dc02889c1e2bff816b0"
+  event: "push"
+  is_fork_pull_request: 0
+  status: 1
+  started: 1683636528
+  stopped: 1683636626
+  created: 1683636108
+  updated: 1683636626
+  need_approval: 0
+  approved_by: 0