Enable eslint import checks and fixed the reported errors (#878)

Summary:
Pull Request resolved: https://github.com/facebook/flipper/pull/878

1) Enabled eslint error reporting for unresolved imports and fixed all the errors
2) Enabled eslint for typings (d.ts) and fixed all the errors

Reviewed By: passy

Differential Revision: D20335151

fbshipit-source-id: 7b142281a406b32df0f02a5cd0d7d05eba941acd

desktop/pkg/src/utils/runBuild.ts

@@ -7,7 +7,7 @@
  * @format
  */
 
-const Metro = require('metro'); // no typings :(
+import Metro from 'metro';
 import * as path from 'path';
 
 function hash(string: string) {