Conditionally hide the search bar in attach menu

[nicolethoen]

If onAttachMenuInputChange is not defined, the attach menu should not render a search bar.
(or there needs to at least be some way to hide the searchbar)

This will support the following proposed Genie pattern: https://www.figma.com/design/lJ5s1z11E4Q2Bp6kD3TE0W/Red-Hat-Genie---MVP?node-id=676-17769&m=dev