Always import config via file-URL

[thw0rted]

Fixes #18

For reference, see nodejs/node#34765:

{on non-Windows platforms} the host-relative URL happens to resolve to the same file. But this is coincidence, not guaranteed

I wanted to add a test for this, but wasn't sure how to make one that loads a config file based on defaultConfigFilePaths.

[75lb]

ahh, well spotted.. don't worry about the test - i'll add that..

[75lb]

ffs, the tests fail as they are on windows.. I usually test manually on Windows before every release but this one has slipped through.. will update the CI to make sure the test suite gets run on a Windows host too..

[75lb]

merged and released in lws v4.0.2.. please let me know if you find anything else.. i'll add Windows testing to the CI later.