consider moving automated tests to a Jest-alternative

[mr-zwets]

Jest isn't the fastest testing framework and we have quite a lot of tests for CahsScript.

Jest also has bad ESM support, so our testing command looks like this

"test": "NODE_OPTIONS='--experimental-vm-modules --no-warnings' jest"

We also still have some .cjs files because of it in the /jest folder

Jest also has a highfootprint, it does have a lot of ecosystem integration but I don't think we use those.

Vitest or AVA or the Deno built-in testing suite all have similar syntax to Jest so should be easy to migrate over to.

CashScript would still have Jest as a DevDependency because of the jestExtensions functionality for the debug tooling...
So the main benefits would be in removed complexity & faster tests