Fix preprocessors tree by wrapping with moduleName

[wondersloth]

This PR addresses the following issues:

• Tree passed to preprocessors for app and addon is not scoped with moduleName #1206
• css file hash doesn't use correct path when generating-scoped-name in embroider app build, when consuming an addon using ecm salsify/ember-css-modules#278

Replicated the issue here:
https://github.com/wondersloth/demo-embroider-preprocessors-bug

In a classic build the tree passed to the preprocessor is scoped with the moduleName.

In embroider, th app or addon tree is not scoped with the name/moduleName

This creates backcompat issues with addons like ember-css-modules that uses the file path to generate hash for some values. Initial attempt fixing from an addon.

• Validated fix via yarn link @embroider/compat in demo-embroider-preprocessors-bug
• Fix v1-app.ts to scope/wrap with moduleName when passing to preprocessors.
• Fix tests so that preprocessors apply transform to my-addon.

[wondersloth]

@ef4 I've got my tests for the preprocessors to pass. FWIW the entire test suite passes for @embroider/compat on my local.

Next would be to validate this more broadly.

[wondersloth]

In my integration testing with the example apps in ember-css-modules, I found another bug.
I need to:

• Move the unwrapping of the moduleName from the files, because the template ast transforms already get the moduleName in the path.