Fix ESLint setup (#240)

In pure javascript eslint config from `@react-native-community`, the no-shadow rule is on,
which is good, but for typescript it generates false-positives and needs a specific configuration change
to use a typescript-specific rule

Reference: 
- https://github.com/typescript-eslint/typescript-eslint/blob/main/packages/eslint-plugin/docs/rules/no-shadow.md
- https://github.com/typescript-eslint/typescript-eslint/issues/2552#issuecomment-691694839

template/_eslintrc.js

@@ -1,4 +1,10 @@
 module.exports = {
   root: true,
   extends: '@react-native-community',
+  parser: '@typescript-eslint/parser',
+  plugins: ['@typescript-eslint'],
+  rules: {
+    'no-shadow': 'off',
+    '@typescript-eslint/no-shadow': ['error'],
+  },
 };

template/package.json

@@ -11,7 +11,7 @@
   },
   "dependencies": {
     "react": "17.0.2",
-    "react-native": "0.66.3"
+    "react-native": "0.66.4"
   },
   "devDependencies": {
     "@babel/core": "^7.12.9",
@@ -20,6 +20,8 @@
     "@types/jest": "^26.0.23",
     "@types/react-native": "^0.66.4",
     "@types/react-test-renderer": "^17.0.1",
+    "@typescript-eslint/eslint-plugin": "^5.7.0",
+    "@typescript-eslint/parser": "^5.7.0",
     "babel-jest": "^26.6.3",
     "eslint": "^7.14.0",
     "jest": "^26.6.3",