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.
