Add page under "Debugging & Test" covering setup / configs for test frameworks

[rschristian]

Inspired from https://github.com/preactjs/preact/discussions/3752

At the moment we don't have any content related to setting up testing frameworks under the "Debugging & Test" section of our docs. If a user was looking to set up Jest aliases, for example, they'd actually need to go to "Getting Started" to get instruction. This leads to poor discoverability.

We could add a "Testing Frameworks" page showing how to setup with Jest, Vitest, etc. and the various preset packages we may already maintain for use. It's much more natural to have test framework config instruction alongside instructions for enzyme and testing-library.