Summary:
I noticed that after the typescript upgrade, I got several weird positives from ESLint (like unused parameters in a type definition, which are obviously always unused, e.g. `type onClick = (e: Event) => void`). After some investigation, it turned out these warnings are generated by eslint, but that those rules should be performaned by typescript/eslint instead. For future reference to which rules this applies:
https://github.com/typescript-eslint/typescript-eslint/blob/master/packages/eslint-plugin/README.md#extension-rules
Updated the config, and while at it, fixed all warnings in our codebase, except for `react-hooks/exhaustive-deps` warnings, since those require semantic changes.
This reduces the amount of eslint warnings from 86 to 39.
Reviewed By: passy
Differential Revision: D23905630
fbshipit-source-id: 0557708fd9ec6b17840a3c191e7d3baf225bdf23
Summary: Our external typings were only effective for the main "app" package. In this diff I've made them effective for all other workspaces too, and also cleaned up typescript configs.
Reviewed By: passy
Differential Revision: D21927361
fbshipit-source-id: ceb8009255583d969d79cc11b20dfe8b686f2fb3
