Add recursive lookup for transitive preview annotations

[trevor-e]

Second part of correctly resolving multi-previews, now we can resolve arbitrary levels of multi-preview annotations.

1. Finds all symbols that have a direct or transitive @Preview annotation by recursively checking annotation classes. Transitive @Preview annotations would be those from a multi-preview.
2. Once we know the symbols annotated with a preview annotation, a second step filters that down to only functions.
3. After we have the functions, we have to then fetch all direct or transitive preview annotations on the function and build up a list of unique snapshot configs. This bit was tricky and does repeat some of the step 1 work from earlier, but not too concerned about the perf impact here.
4. Snapshot generation then proceeds like normal.

Testing:
I created a new @SnapshotTestingPreview and updated some existing previews to use this new annotation. The snapshot output is still the same:

[rbro112]

One nit: Could we make this a separate preview to make sure we can test both the outputs of stacked multipreviews directly on the composable and from the stacked multipreview annotation?

[rbro112]

Current dependencies on/for this PR:

• main
  • PR Add recursive lookup for transitive preview annotations #71 👈
    • PR Add stacked multipreview test #73
      • PR Prepare for Snapshots release 0.8.1 #72

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