Add redirect or rewrite from /projects/macports/ to /

[ryandesign (Ryan Carsten Schmidt)]

Back on macOS forge, it was valid to use the prefix /projects/<projectname> for any Trac URL. So, for example, ​https://trac.macports.org/projects/macports/browser/trunk should redirect to ​https://trac.macports.org/browser/trunk. There are such links in the wild; I just came across one, which is how I discovered that we forgot to set up this redirect on our Trac web server.