Actions Artifacts support uploading multiple files and directories (#24874)

current actions artifacts implementation only support single file
artifact. To support multiple files uploading, it needs:

- save each file to each db record with same run-id, same artifact-name
and proper artifact-path
- need change artifact uploading url without artifact-id, multiple files
creates multiple artifact-ids
- support `path` in download-artifact action. artifact should download
to `{path}/{artifact-path}`.
- in repo action view, it provides zip download link in artifacts list
in summary page, no matter this artifact contains single or multiple
files.

models/migrations/v1_21/v265.go

@@ -0,0 +1,19 @@
+// Copyright 2023 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package v1_21 //nolint
+
+import (
+	"xorm.io/xorm"
+)
+
+func AlterActionArtifactTable(x *xorm.Engine) error {
+	// ActionArtifact is a file that is stored in the artifact storage.
+	type ActionArtifact struct {
+		RunID        int64  `xorm:"index unique(runid_name_path)"` // The run id of the artifact
+		ArtifactPath string `xorm:"index unique(runid_name_path)"` // The path to the artifact when runner uploads it
+		ArtifactName string `xorm:"index unique(runid_name_path)"` // The name of the artifact when
+	}
+
+	return x.Sync(new(ActionArtifact))
+}