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_job.yml

@@ -12,3 +12,17 @@
   status: 1
   started: 1683636528
   stopped: 1683636626
+-
+  id: 193
+  run_id: 792
+  repo_id: 4
+  owner_id: 1
+  commit_sha: c2d72f548424103f01ee1dc02889c1e2bff816b0
+  is_fork_pull_request: 0
+  name: job_2
+  attempt: 1
+  job_id: job_2
+  task_id: 48
+  status: 1
+  started: 1683636528
+  stopped: 1683636626