Some tweaks to CLI configuration

[ryguyk]

Description

• Configures CLI to pass arguments through to the underlying utility.
• Updates CLI help text to explain how to pass args through to underlying utility.
• Displays help text of underlying utility (in addition to general env help) if -h is passed to the yarn script.

These changes allowed the removal of a few yarn scripts:

• lint:staged:test-modified-files: no longer need this because we can pass the necessary commands through to yarn test now and we couldn't before. (Note: before the creation of this now-deleted file, we were simply running jest, but this yarn script was created so as to be able to run the env-loader before running jest. We can now accomplish both by running yarn test and passing arguments through to jest.)
• test:watch: can now run yarn test -- --watch
• test:update-snapshots: can now run yarn test -- -u (Note: We could keep test:watch and test:update-snapshots if we wanted that layer of abstraction, but I'm not sure it's necessary.)

Testing done

Manual testing of yarn scripts

QA steps

• Run yarn scripts and ensure args can be passed through to underlying utility (e.g. jest, next)
• Run yarn scripts with -h and see both general env help and underlying-utility help (e.g. yarn test -h)

[tjheffner]

pulled and tested locally, works great. thank you!

I re-ordered some of the test: commands in package.json and updated test:watch to use the passthrough syntax.

[tjheffner]

I think this comment (or something to that effect) is valuable to keep even if it is technically self-documented in the code

[tjheffner]

not a blocker for this, just curious what failures you were seeing? is it related to fetching an env behind the VA network through GHA (gh-provided vs self-hosted runners), or something else?