Better UI for artifacts browsing

Description

Since v8.12 there is a permalink for accessing artifacts by e.g. branch name, but there is no way to discover it via UI.

Proposal

One possible resolution would be to make an artifacts browser accessible via project, and not a build: image and then to add a dropdown similar to the one in the repository browser for selecting a git ref: image However an additional dropdown for selecting a job would be needed.

An alternative option would be to add a "browse" button in the artifacts download dropdown, but I believe it would become too cluttered.