Remove Flow suppression comments

[kevinbarabash]

It doesn't really make sense to try to maintain these comments since TypeScript will likely require suppressions in different places (or more/less suppressions) than Flow. We can use ts-migrate's ts-ignore plugin to add // @ts-ignore comments for all TypeScript errors that are present after conversion. https://github.com/airbnb/ts-migrate/tree/master/packages/ts-migrate-plugins