Configurable test patterns

[MisanthropicBit]

This is basically the same PR as the one I made here adrigzr/neotest-mocha#2 which allows for user-configurable test patterns instead of having to gradually accommodate more and more patterns.

Other changes

• Fixed a typo(?) in the README about enabling jest_test_discovery.
• Updated/fixed tests as in Support extra_args #106.

[adammfrank]

Anyone want to merge this?

[MisanthropicBit]

@adammfrank @wassimk FYI, I've started a new dev branch on my fork that I intend to keep in sync with the upstream repo and continuously merge select open PRs so I can start using some of these things myself until upstream catches up.