Adding wasm level test fixture and default test

[saga-dasgupta]

Background

Fixes: https://github.com/orgs/shop/projects/147/views/9?pane=issue&itemId=125817929&issue=shop%7Cissues-shopifyvm%7C552

We want to have a way for developers to test their compiled functions for various scenarios and find out when it breaks everytime they make changes to their extension. We want to develop a test suite that they can run which actually builds a function and runs a function with a previous run's logged input and asserts its the same as the logged output.
We are adding a default passing wasm-level test fixture and test to all function extension templates to which developers can add on.
These wasm-level tests replace the unit tests that are baked into the templates.

Solution

I created an app with every type of extension in both JS and Rust and then created a fixture along with a default test that passes, then copied the test directory for each extension over here to its corresponding template so I feel pretty confident in my changes, even though I haven't tophatted it, unsure how I can tophat this.
The package.json in all the test directories are the same. The default.test.js for different extensions have different input query path but is otherwise the same.
There is a second follow-up PR that removes all existing unit tests.
This PR also needs this helper to get published to NPM.

Checklist

• I have 🎩'd these changes
• I have squashed my commits into chunks of work with meaningful commit messages