Update error messages for `/v1/cors` route
Update error messages for `/v1/cors` route

If the request fails (e.g., invalid uri), then respond with 500
and display the error message.

If a `url` query parameter is not found, then response with 404
and display a specific message for the error.

CORSmirror/CORSmirror,CORSmirror/CORSmirror,CORSmirror/CORSmirror