expose access to JLine read calls

[KyleMcB]

This request is specifically for usage in the shell I am writing that uses kotter.

My shell does not create a new tty for each new process. It actually shares its own stdin, stdout, stderr fds. I think all modern *nix shells create a new tty. I have read the source of a unix shell that just forked and exec'd, so this isn't a new way doing things...
Anyways, why is this a problem and why do I need a change in kotter?
When kross launches a child process and stops using its own in/out it has to deterministically stop reading. Else the shell will steal input bytes from the child process. The current api in kotter is a sharedflow that has a tight loop around calling read, so it will also call read again after the point I need it to stop

Describe alternatives you've considered
I also tried adding a way to inject a stop signal into the sharedflow, but the only thing I got to work is direct access to JLine's read call.

PR #125

[bitspittle]

FYI without power over here (in Southern California but in a totally safe place, they're just being cautious). Will review after getting power back, no idea when that will be. Thanks for the PR and explanation!