[Flow202][lib][skip-ci] [9/23] Get rid of BigInt $FlowIssues
Summary:
The new version of Flow supports BigInt, so we can get rid of these.
NOTE: CI will fail on this diff. I considered the possibility of fixing Flow errors BEFORE upgrading Flow, but it wasn't possible... in some cases, the fixes to support the new version of Flow caused errors in the old version. I could have hidden these type errors with $FlowFixMe lines and then later revert those, but that seemed like too much busy work.
Depends on D9700
Test Plan: Confirm the Flow errors go away
Reviewers: atul
Reviewed By: atul
Subscribers: tomek, wyilio
Differential Revision: https://phab.comm.dev/D9701