chore(eslint): use json config instead of js format

VSCode has prompts for json config files but not for js.

-module.exports = {
-  root: true,
-  extends: ['@react-native-community', 'plugin:prettier/recommended'],
-  parser: '@typescript-eslint/parser',
-  plugins: ['@typescript-eslint'],
-};

+{
+  "root": true,
+  "extends": ["@react-native-community", "plugin:prettier/recommended"],
+  "parser": "@typescript-eslint/parser",
+  "plugins": ["@typescript-eslint"],
+  "rules": {
+    "@typescript-eslint/no-unused-vars": "off"
+  }
+}