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Old pr https://github.com/go-gitea/gitea/pull/22345 is outdated after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.

modules/setting/actions.go

@@ -10,7 +10,8 @@ import (
 // Actions settings
 var (
 	Actions = struct {
-		Storage           // how the created logs should be stored
+		LogStorage        Storage // how the created logs should be stored
+		ArtifactStorage   Storage // how the created artifacts should be stored
 		Enabled           bool
 		DefaultActionsURL string `ini:"DEFAULT_ACTIONS_URL"`
 	}{
@@ -25,5 +26,9 @@ func loadActionsFrom(rootCfg ConfigProvider) {
 		log.Fatal("Failed to map Actions settings: %v", err)
 	}
 
-	Actions.Storage = getStorage(rootCfg, "actions_log", "", nil)
+	actionsSec := rootCfg.Section("actions.artifacts")
+	storageType := actionsSec.Key("STORAGE_TYPE").MustString("")
+
+	Actions.LogStorage = getStorage(rootCfg, "actions_log", "", nil)
+	Actions.ArtifactStorage = getStorage(rootCfg, "actions_artifacts", storageType, actionsSec)
 }