The link format CI check is currently silently failing, for example https://github.com/bitcoin/bips/actions/runs/8914643431/job/24482636376.
This failure is caused by Github Actions cloning as little as possible for CI, so the git commands in the script end up failing. This checkout was done in order to check current PRs, however, it’s not much more expensive nor onerous to just always check the links in the entire repo, and would allow this check to actually work. This PR does that, and also fixes the broken link formats in BIPs 197 and 310.
