PR autolinks are rendered in issues section

[nzaytsev]

If there is a PR with id X and no issue with the same id, and we have a branch with the name containing the X substring, it will be handled as PR on the autolinks core side

The lifecycle of autolinks on the branches overview component is:

• match keys from the text (branch name). Non-prefixed keys are always considered as issues (not PRs)
• enrich autolinks (check if the links are available). Github automatically redirects issues to PRs if it possible
• display autolinks as issues

We need to add some protection:

1. pass autolink type and don't show PR autolinks near to issues
2. lock redirect to PR for non-prefixed issue keys