Cleanup qsrelease

[n8henrie]

Since we're relying on qsrelease, I'd like to do a bit of cleanup

• Add / remove quoting where it could and couldn't make a difference respectively
• Make POSIX compliant in case MacOS decides to change default shells again
• More explicit error handling, reporting, and cleanup
• egrep unneeded for word-boundary regex (supported by /usr/bin/grep without -E on monterey)
• grep | sed can be simplified with awk
• add some configuration for local testing (e.g. allow specifying a local cert as a signing identity for testing purposes)
  • Should help with debugging Is signing possible through GitHub Actions? #2576
• prefer --long-arguments for readability

Hopefully the style differences aren't too off-putting, the incoming PR takes suggestions from shellcheck --enable=all --shell=sh

[n8henrie]

Additional issues revealed in this process (present previously but I hadn't noticed in the output, my fault):

• Tests fail with cycle in dependencies #2583

[n8henrie]

Closed: #2582