Add UNIX socket support

[impcyber]

Please describe your feature request:
It would be nice to add support for connecting to the server through a UNIX socket, while simultaneously managing multiple sites on the same server, for example via nginx.
Something like this:
https://github.com/strapi/strapi/blob/master/packages/strapi/lib/Strapi.js#L270

    const listenArgs = this.config.socket
      ? { path: this.config.socket }
      : { host: this.config.host, port: this.config.port };

    if (listenArgs.path) {
      fse.pathExists(this.config.socket, (err, exists) => {
        exists && fse.remove(this.config.socket);
      });
    }

    this.server.listen(listenArgs, err => onListen(err));

https://github.com/strapi/strapi/blob/master/packages/strapi/lib/Strapi.js#L88

socket: '',

https://github.com/strapi/strapi/blob/master/packages/strapi/lib/core/bootstrap.js#L288

strapi.config.socket = _.get(strapi.config.currentEnvironment, 'server.socket') || strapi.config.socket;

[lauriejim]

Hello! Can you please open an RFC.
I suggest you structure your issue there and close this one.
Thank you.

[impcyber]

@lauriejim No problem

[derrickmehaffy]

added in: #7824