Add support for the disabling pesudo terminal in legacy cli mode

[dbrodie]

I am mostly interested in using this project for allowing me to use VSCode remote ssh over tailscale. I am happy to do pull requests if that is preferred.

One of the flags used by VSCode is the -T flag used to disable creating of a pesudo terminal. This flag is only really needed in the legacy cli mode.

[derekg]

Happy take pull request, I just clean off a bunch of silly cruft and make it simple.

[dbrodie]

Implemented in PR:
dbrodie#2

Sorry it didn't really work to split it up into multiple pull requests. The only thing I don't like is that now runSSH has a really long argument list, but not sure if that's ok by you or that is something you would want to change.

[dbrodie]

Sorry, I obviously meant #33