Update regression to use FSHFinder as source

[cmoesel]

Update the regression script to use FSHFinder data as the source of the repository list instead of the static repos-all.txt and repos-select.txt files. As part of this, support --count and --lookback options to restrict the repositories under test.

This still uses the same file format for listing repositories, but now it is generated as a repos.txt file into the output folder first -- and then regression runs on that file. The output repos.txt is generated based on the options selects:

• If no options or --count <number> or --lookback <days> are used, repos.txt is populated w/ repos from FSHFinder
• If the --repo <repos...> option is used, the specified repos are populated in the repos.txt file
• If the --file <path> option is used, the specified file is copies as repos.txt

The CLI has been moved to a new cli.ts file and has the following top-level commands:

Commands:
  run [options]          Find differences in FSH project outputs from one version of SUSHI to another
  list [options]         List repositories found using FSH Finder
  list-legacy [options]  List current repos-all.txt or repos-select.txt file contents without updating them
  update-legacy          Update repos-all.txt using the legacy repository finder logic
  help [command]         display help for command

The list-based commands list out the repositories that would be run as regression without running the regression. This might be useful for debugging or seeing what repos would be run for a particular set of options.

For testing, I recommend seeing what options are available for each command and trying them out. You should also confirm that the NPM scripts work as expected.

[cmoesel]

Dang. I remember thinking to myself that I should double-check that the links still work, and then... I totally forgot. Thanks for spotting it! I think I know how to fix it.

[cmoesel]

Thanks, @mint-thompson. I've fixed this so that now the links are proper relative links. This is an improvement over the old absolute links because now you can move the output folder around (or zip it up) and the links still work.

[cmoesel]

Thanks, @jafeltra. I accepted all of your suggestions.