test: remove WHATWG URL test data file extension

Make url-tests a js file so we can comment out
incompatible tests

PR-URL: https://github.com/nodejs/node/pull/11439


Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Timothy Gu <timothygu99@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>