Redirect with query parameters

#24 (closed) has closed with items for subsequent cycles. While #500 (closed) and #601 (closed) were resolved, there are still a few items from GitLab Pages redirects | GitLab which show that they are not supported. One of them is to support Query Parameters | Redirect options | Netlify Docs.

The description of the feature offers to build up this support in two waves:

You can also use query parameters to more finely control your URL matches.

While our service automatically passes on all query string parameters to destination paths for redirects with 200, 301, and 302 HTTP status, you can also choose to define a redirect path based on a specific parameter or combination of parameters.

1. The first implementation is about amending the default behaviour to "pass on all query string parameters to destination paths"
2. The second implmenetation is about specifying and modifying the desired parameters to pass on.

The use case is to allow to support Webfinger-compatible redirects, which are needed for ActivityPub services that host accounts for a main domain on a subdomain different from that.