[api-extractor] export default of tagged API members are not correctly trimmed from API report variants

[Josmithr]

Summary

Given an export pattern like the following:

/** @beta */
export interface Foo { ... }

export default Foo;

The expectation is that Foo exports would only appear in API report variants beta and alpha, but they incorrectly appear in all report variants like the following:

export { Foo }
export default Foo;

I have published a draft PR (#4774) that illustrates the issue by updating test assets.

[Josmithr]

@octogonz I'm happy to contribute a fix here, but I'll need some guidance on where to get started.

This seems to be specific to cases where an existing export is also exported via export default. E.g.,

/** @beta */
export interface Foo { ... }
export default Foo;

I was not able to repro it when the declaration is inline with the default export. E.g.,

export default interface Foo { ... };