[FEAT] support this in integration tests

[IgnaceMaes]

I would like to see... 🙋‍♀️🙋‍♂️

The codemod should support integration tests making use of the this context.

Why and how 💬

Iterate per test function in the file:

• If no hbs helper, then skip
  • If a template is defined outside test body it's too hard to not break things as in hbs scope semantics are very different
• Loop over all this. usages in the hbs template and list them
• Loop over all this.set usages in the test and list them
• If at least one property is set:
  • Create a new state object at the top of the test function
  • Before the render function, set initial state for every property
    • state.prop1 = this.prop1; ...

const state = new (class {
    @tracked prop1;
    @tracked prop2;
})();

short, but less readable?
OR bit more verbose, but nicer?

class State {
    @tracked prop1;
    @tracked prop2;
};
const state = new State();

OR, but this complicates the template transform as state.x needs a getter

const state = new TrackedMap();

• If at least one property is accessed, but not set:
  • Before the render, create const context = this;
  • Or do const { X, Y } = this;
• Rewrite the template this references to context or state
• Rewrite the this.set expressions
  • to state.prop1 = ...
  • and await settled();
• Import settled from @ember/test-helpers if needed

Additional context ➕

If needed, you can provide more context (e.g. reference materials, screenshots, GIFs) for the request here.