Sunil Mohan Adapa authored Jan 12, 2024 and James Valleroy committed Jan 15, 2024

- Implement continuous reading of stdin and stdout over subprocess.POpen instead
of cliapp.runcmd(). We loose the ability to run multiple commands using a pipe.
This is okay for now.

- Use threads instead of select() to keep the implementation relatively simple.
Overall build performance is unlikely to be effected.

- Use subprocess.run() terminology instead of cliapp terminology.

Tests:

- Run unittests.

- Build amd64 and a20-olinuxino-lime2 targets. The latter failed with slapd
related failures.

- Interrupt the build process in the middle and confirm that cleanups are
happening as expected.

- Confirm that logging output is same as before the changes.

Reviewed-by: James Valleroy <jvalleroy@mailbox.org>