mod_base: controller_page - check if page path equals the request path

This change lets controller_page check if we need to be at a different
URL when the page path of a resource is set.

If set, we need to redirect there if the current request's path is not
equal to the resource's path. This prevents duplicated content on
multiple URLs.

(cherry picked from commit 5cf51471742149763f5db9aaec3127d021f6f70f)