[lib/native/web] convert useInlineEngagementText to getInlineEngagmentSidebarText

Summary:
Small move/rename diff to convert this hook into a general function. This "hook" was not using any react features so this really should just be a function

Depends on D8600

Test Plan: flow and confirmed that native and web apps work fine

Reviewers: atul, kamil

Reviewed By: atul

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D8609