Scripting & documenting debugging one test without anything else in the loop. (#7096)

* A little documentation that shares my quick tips for working in the repository.

* Update startup-testing-debugging.md

* script that shows a menu of tests to pick from & run the debugger on

* debug-test.sh: Refactor CLI help message

* debug-test.sh: documentation update

* debug-test.sh: CLI Help output corrections

* debug-test.sh: minor doc fix

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authored-by: Josh Ramer <ubuntu@ip-172-31-32-53.ec2.internal>
Assisted-by: brian khuu <mofosyne@gmail.com>