refactor: simplify how url generation works

The URLS file is no longer necessary as urls are now generated directly from the app VHOST file.

This also moves all the url generation logic to the domains plugin.

plugins/domains/post-app-rename-setup

@@ -3,12 +3,10 @@ set -eo pipefail
 [[ $DOKKU_TRACE ]] && set -x
 
 trigger-domains-post-app-rename-setup() {
-  declare desc="updates VHOST and URLS files during rename"
+  declare desc="updates VHOST files during rename"
   declare trigger="post-app-rename-setup"
   declare OLD_APP="$1" NEW_APP="$2"
 
-  rm -f "$DOKKU_ROOT/$NEW_APP/URLS"
-
   if [[ -f "$DOKKU_ROOT/$NEW_APP/VHOST" ]]; then
     while read -r VHOST || [[ -n "$VHOST" ]]; do
       sed -i -e "s/$OLD_APP.$VHOST/$NEW_APP.$VHOST/g" "$DOKKU_ROOT/$NEW_APP/VHOST"