Summary:
This diff has three changes:
1. Remove all references to `Stringish` from `NativeDialogManagerAndroid`. (All Fbt objects expose a `.toString` method we could call).
2. Make sure that we only access `DialogManagerAndroid` through `NativeDialogManagerAndroid`.
3. Removed a bunch of `$FlowFixMes` in the files I touched. Probably not the best idea to bite into this cleanup on this diff, but what's done is done.
Since this diff is fairly large, I've commented on parts of it I thought were note-worthy. I've also commented on the changes I had to make to fix flow after removing the `$FlowFixMe`s.
Reviewed By: PeteTheHeat
Differential Revision: D16428855
fbshipit-source-id: 0e6daf2957f4b086ebb1e78e0a59930668c65576