Having postgresql.org link to cgit instead of gitweb

Hi,

While prepping the website for the PG18 GA, I stumbled on the inability
to access parts of commits through the gitweb links, specifically
hitting 429 status code errors (this seems to be intermittent). After
some briefing on why it's disabled and how this isn't an issue with
cgit, I prepped a patch for postgresql.org (the main website) that would
update the git.postgresql.org reference to use cgit instead of gitweb.

However, as this could impact some hacker workflows (e.g. the commit
search page), I wanted to run this patch by -hackers before committing.
Basically, the patch:

* Moves any web links to git.postgresql.org repos to use the cgit
interface instead of gitweb (e.g. [1])
* Update the commit search[2] to use cgit instead of gitweb

Please note that this doesn't impact the availability of gitweb, rather
the main parts of the postgresql.org website will link to cgit first,
and people will have a more consistent experience overall (e.g. no 429
errors).

Thoughts?

Thanks,

Jonathan

[1] https://www.postgresql.org/developer/related-projects/
[2] https://www.postgresql.org/developer/coding/