Run a program under a pseudo terminal. This is used by run_init to run actually run the program after
setting up the proper context. This program acquires a new Pseudo terminal, forks a child process that
binds to the pseudo terminal, and then sits around and connects the physical terminal it was invoked upon
with the pseudo terminal, passing keyboard input into to the child process, and passing the output of the
child process to the physical terminal.
It sets up the pseudo terminal properly based on the physical terminal attributes, and then sets the
user's terminal to RAW mode, taking care to reset it on exit.