Check permanent redirects

[honzajavorek]

This is more of a suggestion or an idea for future, and a #944 spin-off. We already check links. Sometimes the target changes and we link through unnecessary redirects. There are several types of redirects, but it boils down to:

• Temporary redirects,
• permanent redirects, when the content moves.

In case of the permanent ones, we can just update our links so they point to new places, saving readers' time and unnecessary hops, and also lowering the chance that the link breaks completely.

I think it's okay to check permanent redirects only from time to time, as a matter of regular seasonal gardening, rather than having the check under each PR.

As @TC-MO pointed out, this could be done by disallowing HTTP status codes for permanent redirects in Lychee configuration. I'm creating this issue as a note for myself that I want to do this locally and send a PR with updated links.

[honzajavorek]

Running Lychee locally with --max-redirects 0 is probably the best approximation of what I had in mind, but it's quite a manual process to go through the links and fix them. It does detect a lot of interesting issues though:

• Some links are just broken, but the target site returns a redirect instead of error.
• Some links redirect to existing pages, but those are nonsense in the original context, and need to be fixed.
• A lot of old links within the Apify realm itself.
• Some links redirect to new places, but it's clear that they're midway to become broken. Updating them or the context of the link prolongs their life.

I'll be sending a one-off PR to demonstrate usefulness of doing this regularly, but I'll leave up to the rest of the team if they wish to build a respective infrastructure. I feel like I'm stepping outside of my Academy garden here.