We call removeEditMode in native/navigation/tab-router.js, so it needs to be able to support a TabAction as well as ChatRouterNavigationAction. Separating this diff out because the changes are non-obvious.
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 D10020