Move repetitive code from Options.matchRedirects into a new
Redirect.rewriteURL method and add a new test file.
No functional changes are intended; this is in preparation
for a later change to address #269.
Reviewed-on: https://codeberg.org/Codeberg/pages-server/pulls/304
Reviewed-by: crapStone <codeberg@crapstone.dev>
Co-authored-by: Daniel Erat <dan@erat.org>
Co-committed-by: Daniel Erat <dan@erat.org>
