TU/Package Maintainer rename

To comply with the https://gitlab.archlinux.org/archlinux/tu-bylaws/-/merge_requests/6 merge request about the rename of TUs to Package Maintainers, some URLs and directories will have to updated/renamed on Aurweb's side.

Here's what I could list:

• Rename the dedicated TU url from "https://aur.archlinux.org/tu/" to "https://aur.archlinux.org/package-maintainer/" as well as the "Trusted User" link button to it in the top menu.
• Rename the "Trusted User" account type to "Package Maintainer", as well as the "Trusted User & Developer" one to "Package Maintainer & Developer" when querying an account via https://aur.archlinux.org/accounts.
• Rename the bylaws url from "https://aur.archlinux.org/trusted-user/TUbylaws.html" to "https://aur.archlinux.org/package-maintainer/package_maintainer-bylaws.html" and the related redirection from "https://tu-bylaws.aur.archlinux.org/" to "https://package_maintainer-bylaws.aur.archlinux.org/".
• Rename the dedicated directory on Aurweb's server from "${aurweb_root}/web/html/trusted-user/" to "${aurweb_root}/web/html/package-maintainer/"

I remain available if needed 🙂