The daemon by default listens for RPC over a socket.
Before this change, this socket was a TCP/IP network socket (over localhost),
but now we change it to be a unix domain socket by default (if available).
This socket is used not only when sending commands over JSON-RPC,
but also when using the CLI, and to a tiny extent even used when running the GUI.
The type of socket used (and hence this change) is invisible to CLI and GUI users.
JSON-RPC users might want to use either the --rpcsock CLI flag
or set the "rpcsock" config key (to "tcp") to switch back to using a TCP/IP socket.
In practice it seems unix domain sockets are available on
all mainstream OSes/platforms, except for Windows.
closes https://github.com/spesmilo/electrum/issues/7553