[Improvement] Option for permanent redirect vs temporary in www -> non-www setting.

[jillesme]

Hello,

I'd love an option to change www redirect from 302 (temporary) to 301 (permanent). Currently my Trafaek config has:

traefik.http.middlewares.1-a48sg8048sg12304k0c8gs8o4-to-non-www.redirectregex.permanent=false

Which redirects all www to non-www with a 302. However, I want this to be a permanent redirect and I assume others too. Perhaps a checkbox with "Permanent?" when selecting www/non-www would do the trick!

If this is something you'd like, I'd be happy to raise a PR!