redirect trac wiki URLs to active GitLab wikis, not legacy

TL;DR: please comment with the redirection pattern, pages, or set of pages you want redirected, and to where. opening a new issue also works, and in fact easier for us to track, especially for large changes. (example ticket: #40236 (closed).) thanks!

In tpo/anti-censorship/pluggable-transports/snowflake#40031 we wanted to make the Snowflake trac wiki page send people to the right gitlab wiki, not the frozen legacy copy of the trac page since it is becoming more and more wrong.

@anarcat suggested that the first step would be to add a rewriterule for the trac.tpo config, for each trac wiki page that now has a better location. I gave that a try right now with

+        RewriteRule ^/projects/tor/wiki/doc/Snowflake$ https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/-/wikis/ [R]

If it works, I'm guessing we'll want to do that trick again with many more wiki pages, which is what this ticket is about.

Note also: it appears we set up the trac redirects with [R], not [R=301], so right now we're telling google et al that we might change our mind at any moment and put all the content back on trac.tpo. That's probably ok for the short term, but at some point we'll want to turn it into a 301, not a 302.