Disable ESLint no-undef for TypeScript files (#32655)

Summary:
The `typescript-eslint` project [recommends that `no-undef` is disabled for TypeScript files](https://github.com/typescript-eslint/typescript-eslint/blob/6c3816b3831e6e683c1a7842196b34248803d69b/docs/linting/TROUBLESHOOTING.md#i-get-errors-from-the-no-undef-rule-about-global-variables-not-being-defined-even-though-there-are-no-typescript-errors), since TypeScript itself will perform this check. Disabling this config property has two benefits:

- Undefined variables and types will only be reported once, by the TypeScript compiler. Currently they are reported twice: once by TypeScript, and once by ESLint:

<img width="506" alt="Screenshot 2021-11-24 at 12 38 22" src="https://user-images.githubusercontent.com/820863/143239961-eb8ed709-60f9-490a-bda3-fc581673d56c.png">

- Types that are declared globally by React Native will no longer be erroneously reported as undefined - this is currently the case for some types, e.g. `Blob`:

<img width="419" alt="Screenshot 2021-11-24 at 12 40 04" src="https://user-images.githubusercontent.com/820863/143240213-06428b24-09c8-4f95-8e77-7f4fd160eed1.png">

## Changelog

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[General] [Fixed] - ESLint no-undef rule clashing with TypeScript compiler for TS files

Pull Request resolved: #32655

Test Plan:
- Before: ESLint reporting on undefined variables in TypeScript files
- After: ESLint no longer reporting on undefined variables in TypeScript files

Reviewed By: GijsWeterings

Differential Revision: D32647147

Pulled By: yungsters

fbshipit-source-id: 070c734ac7a075b556492726c8fecf4fdab65898

packages/eslint-config-react-native-community/index.js

@@ -58,6 +58,7 @@ module.exports = {
         'no-unused-vars': 'off',
         'no-shadow': 'off',
         '@typescript-eslint/no-shadow': 1,
+        'no-undef': 'off',
       },
     },
     {