Indexed Access Types: Revised

[sinclairzx81]

@xddq Hey, just submitting and updated PR for the Indexed Access Types. Wanted to simplify the accessor resolution and avoid the property collection / depth introspection https://github.com/sinclairzx81/typebox-codegen/pull/2/files#diff-2d6cde5bd1603d51af990557190f42976eba2d85f2a87556bc5535d0e18c3b2cR118-R248

Implementation of Indexed Accessor Types is basically just reduced to the following (where we trust the compiler to produce the correct objectType and indexType. The output just yields a T.properties[key]. This function is called from the Visit(node) function.

function* IndexedAccessType(node: ts.IndexedAccessTypeNode): IterableIterator<string> {
  const obj = node.objectType.getText()
  const key = node.indexType.getText()
  yield `${obj}.properties[${key}]`
}

This PR also implements unit tests for the model transformation. To keep dependencies to an absolute minimum (and to avoid babel side dependencies), I'm trialing the new Node test runners https://nodejs.org/api/test.html. These are built into Node nowadays and should be supported on modern versions Node16, 18 and 19 (I'm running 18 LTS this side). These seem to work ok (but the test filtering Node implemented needs work).

I usually use mocha, but depending on how well Node test runners hold up, can swap to Jest as the setup should largely be the same.