First steps towards adding jsTerm support.

Copied the novnc.html to jsterm.html.  This will require some tweaking
before jsTerm itself can be added.

refs #15495
Renamed VNC proxy to console proxy.

Mostly cosmetic but still necessary.

refs #15495
Added ssh_proxy() and a URL to reference it.

This will give jsTerm something to hang its socket on.

refs #15495