Implement actions artifacts (#22738)

Implement action artifacts server api.

This change is used for supporting
https://github.com/actions/upload-artifact and
https://github.com/actions/download-artifact in gitea actions. It can
run sample workflow from doc
https://docs.github.com/en/actions/using-workflows/storing-workflow-data-as-artifacts.
The api design is inspired by
https://github.com/nektos/act/blob/master/pkg/artifacts/server.go and
includes some changes from gitea internal structs and methods.

Actions artifacts contains two parts:

- Gitea server api and storage (this pr implement basic design without
some complex cases supports)
- Runner communicate with gitea server api (in comming)

Old pr https://github.com/go-gitea/gitea/pull/22345 is outdated after
actions merged. I create new pr from main branch.


![897f7694-3e0f-4f7c-bb4b-9936624ead45](https://user-images.githubusercontent.com/2142787/219382371-eb3cf810-e4e0-456b-a8ff-aecc2b1a1032.jpeg)

Add artifacts list in actions workflow page.

routers/web/web.go

@@ -1192,6 +1192,8 @@ func registerRoutes(m *web.Route) {
 				})
 				m.Post("/cancel", reqRepoActionsWriter, actions.Cancel)
 				m.Post("/approve", reqRepoActionsWriter, actions.Approve)
+				m.Post("/artifacts", actions.ArtifactsView)
+				m.Get("/artifacts/{id}", actions.ArtifactsDownloadView)
 				m.Post("/rerun", reqRepoActionsWriter, actions.RerunAll)
 			})
 		}, reqRepoActionsReader, actions.MustEnableActions)