Fix most lint warnings

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

desktop/plugins/fresco/ImagesCacheOverview.tsx

@@ -20,7 +20,6 @@ import {
   FlexColumn,
   LoadingIndicator,
   styled,
-  Select,
   ToggleButton,
   Text,
 } from 'flipper';
@@ -96,13 +95,6 @@ type ImagesCacheOverviewState = {
   size: number;
 };
 
-const _StyledSelect = styled(Select)({
-  marginLeft: 6,
-  marginRight: 6,
-  height: '100%',
-  maxWidth: 164,
-});
-
 export default class ImagesCacheOverview extends PureComponent<
   ImagesCacheOverviewProps,
   ImagesCacheOverviewState