ui: Clean up `PlatformTitlebar` implementation (#9413)

This PR cleans up the implementation of the `PlatformTitlebar` component
to better match our conventions for building UI components.

Release Notes:

- N/A

Marshall Bowers committed 2y ago

123d3ee282f23073ecc2f24138e24f88f82e50f7

Parent: db43479

Committed by GitHub <noreply@github.com> on 3/15/2024, 6:31:02 PM