[Due for payment 2025-08-26] [Suggested Search v2.4] [App] Implement Group By Members Header

[JS00001]

Implement this section of the design doc: https://docs.google.com/document/d/1vXMf1oK3J8A7EcjTGSPtpT2rgHWqcAg-FbuXlObjHZ4/edit?tab=t.0#bookmark=id.ib8lfumzy84z

Issue Owner

Current Issue Owner: @JmillsExpensify

[JS00001]

This is deployed, but also hidden behind a dev lock while waiting for BE changes. The FE changes dont yet support the future BE changes, but the skeleton is there

[JS00001]

FE changes are in, still need to integrate w/ backend, which is still being discussed