LibMan download is flaky when fetching a GitHub by ref (OSOE-1210)

[sarahelsaig]

The current configuration of using jsDelivr for downloading NPM packages is very reliable for actual NPM packages. But it occasionally fails in GH runs when building Lombiq.UIKit. Specifically this project, because it references slick from GitHub using a commit ref as version instead of a release NPM package. I think in this use-case jsDelivr is only proxying to GH, and GH isn't super reliable as a CDN.

Possible solutions:

• See if we can do retries with some wait time on failure. (the downloader already does 3 tries, but there is no time gap)̇.
• Implement caching in the GitHub runner, for all libman or just specifically for GitHub-sourced libraries (slick it the only one at the time).
• ???

Jira issue

[Piedone]

Example of such a failing build: https://github.com/Lombiq/Open-Source-Orchard-Core-Extensions/actions/runs/20063176567/job/57544958986

Only jsdelivr supports this, so we can't try switching to the other providers.

Opened aspnet/LibraryManager#820. Until this can be fixed better, I'm adding slick to the repo.

[Piedone]

To also reflect on the possible solutions and why I didn't go down that route:

• While I suppose we could somehow add retries by injecting something into the middle of the MSBuild pipeline, retries is something that really needs to be done (rather, utilized) in LibMan itself. This needs very little additional work, since the retry logic is there but doesn't seem to be utilized in this particular case, see the issue I opened.
• Performance-wise caching is not necessary (or can potentially also be detrimental, because the storage of actions/cache is not necessarily faster than jsdelivr), so i wouldn't do it for that. For reliability, it can perhaps work, but due to the cache being invalidated, not sure how much we'd gain overall.

Opened a PR for this.

[Piedone]

Apparently, putting the files into the repo didn't fix this: https://github.com/Lombiq/Open-Source-Orchard-Core-Extensions/actions/runs/20195665809/job/57979257223.