sysutils/orch: add a new port for program orchestration

Inspired by expect(1) but with its own syntax, orch allows program
orchestration via a pts(4) pseudo-terminal driven by similar write/match
patterns as with it source of inspiration.

This is still in relatively early development, but already it has a fair
amount of useful features.  Feedback is welcome, examples can be found
both in the manpage as well as /usr/local/share/orch/examples.  Other
practical examples can be found at:

https://git.kevans.dev/kevans/tty-tests