Bug 1914145 - Create initial search component stub.

[Standard8]

This adds a skeleton search component and mechanics, which we will build on in subsequent PRs. I don't think it needs a changelog entry, as this isn't really adding functionality, but can add one if needed.

Pull Request checklist

• Breaking changes: This PR follows our breaking change policy
  • [X] This PR follows the breaking change policy:
    • This PR has no breaking API changes, or
    • There are corresponding PRs for our consumer applications that resolve the breaking changes and have been approved
• [X] Quality: This PR builds and tests run cleanly
  • Note:
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    • If this pull request includes a breaking change, consider cutting a new release after merging.
• [X] Tests: This PR includes thorough tests or an explanation of why it does not
• [X] Changelog: This PR includes a changelog entry in CHANGELOG.md or an explanation of why it does not need one
  • Any breaking changes to Swift or Kotlin binding APIs are noted explicitly
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  • Any new dependencies are accompanied by a summary of the due diligence applied in selecting them.

Branch builds: add [firefox-android: branch-name] to the PR title.