Support using Client Certificate for HTTPS

[SoulKa]

Is your feature request related to a problem? Please describe.
Some self-hosted webservers require a client certificate for communication.

Describe the solution you'd like

• A collection setting that allows setting a client certificate, key, and optionally CA certificate(s) as file input
• The backend uses the filepaths configured in the collection setting and reads the certificates and key
• The certificates are configured using undici before executing the HTTP request

Describe alternatives you've considered

• It might make sense to allow this to be configured on a folder or request level just as authentication

Additional context

• See example on how to use client certificates in Undici