Add ability to generate a single finding

[oboyle]

I would like the ability to generate one type of finding using the script, ideally passed on the command line.

[scottbward]

If this is an ask to generate different finding types than this tester already produces, please provide the details about those additional findings. Not all types of findings can be supported by this tester but we can evaluate. It is unlikely that this tester will be modified to only generate a subset of the findings that it currently supports, however the findings can be filtered in the console and through EventBridge if you only care about specific findings.