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Old pr https://github.com/go-gitea/gitea/pull/22345 is outdated after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

@@ -16,6 +16,7 @@ import (
 	"code.gitea.io/gitea/modules/actions"
 	"code.gitea.io/gitea/modules/base"
 	context_module "code.gitea.io/gitea/modules/context"
+	"code.gitea.io/gitea/modules/storage"
 	"code.gitea.io/gitea/modules/timeutil"
 	"code.gitea.io/gitea/modules/util"
 	"code.gitea.io/gitea/modules/web"
@@ -418,3 +419,80 @@ func getRunJobs(ctx *context_module.Context, runIndex, jobIndex int64) (*actions
 	}
 	return jobs[0], jobs
 }
+
+type ArtifactsViewResponse struct {
+	Artifacts []*ArtifactsViewItem `json:"artifacts"`
+}
+
+type ArtifactsViewItem struct {
+	Name string `json:"name"`
+	Size int64  `json:"size"`
+	ID   int64  `json:"id"`
+}
+
+func ArtifactsView(ctx *context_module.Context) {
+	runIndex := ctx.ParamsInt64("run")
+	run, err := actions_model.GetRunByIndex(ctx, ctx.Repo.Repository.ID, runIndex)
+	if err != nil {
+		if errors.Is(err, util.ErrNotExist) {
+			ctx.Error(http.StatusNotFound, err.Error())
+			return
+		}
+		ctx.Error(http.StatusInternalServerError, err.Error())
+		return
+	}
+	artifacts, err := actions_model.ListUploadedArtifactsByRunID(ctx, run.ID)
+	if err != nil {
+		ctx.Error(http.StatusInternalServerError, err.Error())
+		return
+	}
+	artifactsResponse := ArtifactsViewResponse{
+		Artifacts: make([]*ArtifactsViewItem, 0, len(artifacts)),
+	}
+	for _, art := range artifacts {
+		artifactsResponse.Artifacts = append(artifactsResponse.Artifacts, &ArtifactsViewItem{
+			Name: art.ArtifactName,
+			Size: art.FileSize,
+			ID:   art.ID,
+		})
+	}
+	ctx.JSON(http.StatusOK, artifactsResponse)
+}
+
+func ArtifactsDownloadView(ctx *context_module.Context) {
+	runIndex := ctx.ParamsInt64("run")
+	artifactID := ctx.ParamsInt64("id")
+
+	artifact, err := actions_model.GetArtifactByID(ctx, artifactID)
+	if errors.Is(err, util.ErrNotExist) {
+		ctx.Error(http.StatusNotFound, err.Error())
+	} else if err != nil {
+		ctx.Error(http.StatusInternalServerError, err.Error())
+		return
+	}
+	run, err := actions_model.GetRunByIndex(ctx, ctx.Repo.Repository.ID, runIndex)
+	if err != nil {
+		if errors.Is(err, util.ErrNotExist) {
+			ctx.Error(http.StatusNotFound, err.Error())
+			return
+		}
+		ctx.Error(http.StatusInternalServerError, err.Error())
+		return
+	}
+	if artifact.RunID != run.ID {
+		ctx.Error(http.StatusNotFound, "artifact not found")
+		return
+	}
+
+	f, err := storage.ActionsArtifacts.Open(artifact.StoragePath)
+	if err != nil {
+		ctx.Error(http.StatusInternalServerError, err.Error())
+		return
+	}
+	defer f.Close()
+
+	ctx.ServeContent(f, &context_module.ServeHeaderOptions{
+		Filename:     artifact.ArtifactName,
+		LastModified: artifact.CreatedUnix.AsLocalTime(),
+	})
+}