Upgrading flow and fixing lint errors

Summary:
Upgrading to flow 0.91, fixing a bunch of `$FloxFixMe`s that were introduced by upgrading to 0.86.
Also fixing some linting issues.

Reviewed By: priteshrnandgaonkar

Differential Revision: D13900794

fbshipit-source-id: 5d0a1b62371f3b5d34b909bae0876583acb6f977

src/createTablePlugin.js

@@ -58,7 +58,6 @@ type State = {|
  * the client in an unknown state.
  */
 export function createTablePlugin<T: RowData>(props: Props<T>) {
-  // $FlowFixMe persistedStateReducer is fine to accept payload of type T, because it is of type RowData
   return class extends FlipperPlugin<State, *, PersistedState<T>> {
     static keyboardActions = ['clear', 'createPaste'];