Feature request: Aupport arbitrary headers in HTTP request

[bvajk]

Is your feature request related to a problem? Please describe.
I was trying to use the HTTP request with an azure function which requires an x-function-key header, but I was confronted with the error message HTTP request - TypeError in blob ... invalid header name
I might have missed it, but I don't see an option anywhere to allow custom kind of headers

Describe the solution you'd like
Maybe my suggestion would be a simple checkbox on the http request node for allowing not to validate header names

Describe alternatives you've considered
Another alternative would be to simply disable validation overall without that checkbox, but that would probably be more intrusive on seasoned users

Additional context
none