[lib] Fix incorrect timestamps for sidebars

Summary:
This addresses ENG-9951:

1. Fixes useSidebarInfos's initial ordering to sort on lastUpdatedAtLeastTime (a number) instead of lastUpdatedTime (a promise). Flow failed to catch this because Lodash's usage is hard to type.
2. Fixes lastUpdatedTimeIncludingSidebars to consider all sidebars, instead of trusting the first one in the initial order to have the most recent timestamp.
3. Fixes getAllFinalSidebarItems to reorder after all promises resolve.

Test Plan: Tested on both native (my iOS device running a Release build pointed at prod) and web (my comm.software staging environment that uses prod data)

Reviewers: varun, will

Reviewed By: will

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D13984