Add a headers parameter to the form

[Neodelf]

Is your feature request related to a problem? Please describe.
The form accepts a path, method and body parameters. There is not possible to set the headers of a request.

Describe the solution you'd like
It would be great to add a headers parameter to the form.

Additional context
I think it could be helpful to have a text field for the headers parameter. They could be divided by symbol, for example ;.