Angular: Handle nested module metadata

[valentinpalkovic]

Closes #24636

What I did

Handling a case, where meta data, extracted from modules, is returned as nested arrays. E.g., where metadata from a particular NgModule should look like declarations: [DropDownListComponent], it sometimes is extracted as declarations: [[DropDownListComponent]]. Flattening these declarations before processing fixes the issue.

Checklist for Contributors

Testing

The changes in this PR are covered in the following automated tests:

• stories
• unit tests
• integration tests
• end-to-end tests

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Documentation

• Add or update documentation reflecting your changes
• If you are deprecating/removing a feature, make sure to update
  MIGRATION.MD

Checklist for Maintainers

• When this PR is ready for testing, make sure to add ci:normal, ci:merged or ci:daily GH label to it to run a specific set of sandboxes. The particular set of sandboxes can be found in code/lib/cli/src/sandbox-templates.ts

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  Available labels

  • bug: Internal changes that fixes incorrect behavior.
  • maintenance: User-facing maintenance tasks.
  • dependencies: Upgrading (sometimes downgrading) dependencies.
  • build: Internal-facing build tooling & test updates. Will not show up in release changelog.
  • cleanup: Minor cleanup style change. Will not show up in release changelog.
  • documentation: Documentation only changes. Will not show up in release changelog.
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🦋 Canary release

This pull request has been released as version 0.0.0-pr-24798-sha-f16de2fb. Install it by pinning all your Storybook dependencies to that version.

More information

Published version	0.0.0-pr-24798-sha-f16de2fb
Triggered by	@valentinpalkovic
Repository	storybookjs/storybook
Branch	valentin/angular-component-part-of-two-declarations
Commit	f16de2fb
Datetime	Fri Nov 10 09:44:14 UTC 2023 (1699609454)
Workflow run	6823202443

To request a new release of this pull request, mention the @storybookjs/core team.

core team members can create a new canary release here or locally with gh workflow run --repo storybookjs/storybook canary-release-pr.yml --field pr=24798