Server.newSession(named:startDirectory:windowName:)

Sessions can be created without a session name (0.14.2+):

>>> server.new_session()
Session($2 2)

Creating them in succession will enumerate IDs (via tmux):

>>> server.new_session()
Session($3 3)

With a `session_name`:

>>> server.new_session(session_name='my session')
Session($4 my session)

const created = await server.newSession({ name: "work" });
created.name; // "work"