Support Sending RPC Requests to Bitcoin Core Over Unix Socket

[robertmin1]

It would be great to support sending RPC requests to Bitcoin Core over a Unix socket. Bitcoin Core only supports RPC over HTTP. To work around this limitation, we can send HTTP requests over a Unix socket and then redirect them to the Bitcoin Core server using a program such as socat. This approach has been tested and works without any issues.

I wanted to get your input before working on a PR. This will only involve adding a config field for the socket path and adding a Dial Context to the HTTP client + Explanation on how to use it

Here is an example of http over unix socket: https://gist.github.com/teknoraver/5ffacb8757330715bcbcc90e6d46ac74#file-unixhttpc-go-L27-L31
Benefits: Security