[lib/native/web] convert appendSuffix to useAppendCommunitySuffix

Summary: As I was working on the new navigation sidebar, I noticed that all uses of appendSuffix was being wrapped in a useMemo. To "improve the neighborhood" I converted appendSuffix into a hook and factored out the useMemo into the hook

Test Plan: flow and confirmed that there were no regressions with the community names in the community drawer

Reviewers: atul, rohan, kamil

Reviewed By: rohan

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D10349