feat: Add headers to quick

[JonForest]

I've added a --headers option to the artillery quick command.

Sorry I've not added tests; that batch file stuff is a little beyond me. I have manually tested this with an authorisation token, and it seems to work fine.

[JonForest]

Sorry about the delay in fixing up the conflict.

[JonForest]

As far as I can tell, this job didn't actually fail tests?

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