Add test library integrations

[reibitto]

I'd like to add integrations for the popular test frameworks:

• scalatest
• MUnit
• specs2
• zio-test

I'm not sure exactly what that entails just yet, but at the very least automatic creation/shutdown of the VCR HTTP client in before/after blocks (or whatever the equivalent is in each testing framework).

Maybe automatically picking up the spec/test name and saving it with that filename could be helpful too.