Feature request: set source-interface

[sebbbastien]

Hi,

I'm working on network appliances which have non-trivial routing setup.
I need to be able to choose the source interface for DNS queries.

I've already wrote a kind of "patch" to be able to choose source-interface from CLI (here)

Can you help me to finalize this patch to be able to submit a clean pull-request?
I think the first step is to add this --iface option to others resolvers (TCP, DOH, DOT, DOQ and DNSCrypt).

What are the others steps/needs?

BR