The first thing I'm working on is fixing Flow errors with the new version of Flow, so I'll start by upgrading Flow.
The new version of Flow adds support for enums, which I'm enabling here based on the lead of the React Native .flowconfig.
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 D9690