Add releases/latest{file} route

[dboreham]

Possible partial fix (the "download url for latest release" part) for #3712
Draft PR posted for comment, tests currently missing.

[JakobDev]

{repo}/releases/latest is already a existing download link. So you should use {repo}/releases/latest/{filename} instead of {repo}/releases/download-latest/{filename}. A big problem I see here, is that many Projects tend to include the Version on the filename.

[dboreham]

I don't think {repo}/releases/latest works here because it only redirects to the specific release page.
It doesn't allow for downloading a named artifact from the latest release, like:

$ curl http://gitea.local:3000/org/repo/releases/download-latest/file

[JakobDev]

I know, that currently you can't download through {repo}/releases/latest, as it's only a redirect. I was suggest, that you use {repo}/releases/latest/{file} instead of {repo}/releases/download-latest/{file}as route in this PR, as this is more intuitive.

[dboreham]

I was suggest, that you use {repo}/releases/latest/{file} instead of {repo}/releases/download-latest/{file}as route in this PR

I didn't do that because the download route seems to be subject to different auth checks and I don't understand enough about the routing library to know if that would be problematic. But if you think it's ok, it's fine with me.

[dboreham]

Pushed a commit that changes the path to {repo}/releases/latest/{file}.
Manually tested. Auth works as expected (unauthenticated access to {repo}/releases/latest/{file} is permitted while still disallowed to {repo}/releases/latest).

Now looking at how to add a test...

[dboreham]

I found existing tests here: https://github.com/go-gitea/gitea/blob/main/tests/integration/api_releases_test.go but doesn't look like there is a test for download already. I will look at adding one for the existing download, and the latest release download code added in this PR.

[silverwind]

Should we expose the new link on UI somewhere?

[dboreham]

Should we expose the new link on UI somewhere?

I'm not sure. GH just documents this (search for "Linking to the latest release").

[silverwind]

A test would be nice, likely in tests/integration/release_test.go.

[dboreham]

Closing because this PR has already been merged. It seems to achieve roughly the same goal, except presumably will cause problems if anyone ever makes a real tag named "latest". This PR handled that case by using a distinct route rather than overloading the meaning of the vTag.