Upgrade Prettier from 1.17 to 2.0.2.

Summary:
This gets us on the latest Prettier 2.x:
https://prettier.io/blog/2020/03/21/2.0.0.html

Notably, this adds support for TypeScript 3.8,
which introduces new syntax, such as `import type`.

Reviewed By: zertosh

Differential Revision: D20636268

fbshipit-source-id: fca5833d003804333a05ba16325bbbe0e06d6c8a

desktop/static/transforms/__tests__/electron-stubs.node.js

@@ -21,5 +21,5 @@ test('transform electron requires to inlined stubs', () => {
   const transformed = transform(src, babelOptions).ast;
   const body = transformed.program.body[0];
   expect(body.type).toBe('ExpressionStatement');
-  expect(body.expression.properties.map((p) => p.key.name)).toContain('remote');
+  expect(body.expression.properties.map(p => p.key.name)).toContain('remote');
 });