Exclude generated code from lint (#54530)

Summary:
I was experimenting with TS API in the monorepo, and spotted that root lint tries to format generated code.

This small change add exclusion for files in `private/react-native-codegen-typescript-test/lib` which are generated locally when running TS API tests. The path is already ignored in `.gitignore` file:
* https://github.com/facebook/react-native/blob/main/.gitignore#L146-L146

## Changelog:

[INTERNAL] [FIXED] - Exclude generated code from lint checks to avoid unnecessary warnings.

Pull Request resolved: #54530

Test Plan: Running `yarn lint` at monorepo root no longer outputs warnings.

Reviewed By: cortinico

Differential Revision: D86963479

Pulled By: cipolleschi

fbshipit-source-id: e067bbbbf69d24929095aed1145f41ae9f26fbd4

Author: Simek

.eslintignore

@@ -13,6 +13,7 @@ packages/*/dist
 packages/*/types_generated
 packages/debugger-frontend/dist/**/*
 packages/react-native-codegen/lib
+private/react-native-codegen-typescript-test/lib/**/*
 **/Pods/*
 **/*.macos.js
 **/*.windows.js