fix(app): Fix Node 12 fs/promises error in AppDelegate Expo plugin

[barthap]

Description

#5584 (comment)
I feel bad at myself not double-checking this earlier. 🤦

Related issues

#5584

Test Plan

This time checked that it is the only occurrence of fs/promises in published v12.5.0:

mkdir rnfb_fs_promises && cd rnfb_fs_promises
yarn init
yarn add @react-native-firebase/app @react-native-firebase/perf @react-native-firebase/crashlytics
grep -r fs/promises node_modules

The grep output:

~/dev/temp/rnfb_fs_promises » grep -r fs/promises node_modules
node_modules/@react-native-firebase/app/CHANGELOG.md:- **app, expo:** Use `fs/promises` in Node 12 compatible way ([#5585](https://github.com/invertase/react-native-firebase/issues/5585)) ([64f569a](https://github.com/invertase/react-native-firebase/commit/64f569acd2cea284baa305451df9533f138539e7))
node_modules/@react-native-firebase/app/plugin/build/ios/appDelegate.js:const promises_1 = __importDefault(require("fs/promises"));

---

The react-native-firebase repository still have some occurences in __tests__ but they're not used in prod nor published:

~/dev/react-native-firebase(master) » grep -r fs/promises . 
./CHANGELOG.md:* **app, expo:** Use `fs/promises` in Node 12 compatible way ([#5585](https://github.com/invertase/react-native-firebase/issues/5585)) ([64f569a](https://github.com/invertase/react-native-firebase/commit/64f569acd2cea284baa305451df9533f138539e7))
./packages/crashlytics/plugin/__tests__/androidPlugin.test.ts:import fs from 'fs/promises';
./packages/app/CHANGELOG.md:- **app, expo:** Use `fs/promises` in Node 12 compatible way ([#5585](https://github.com/invertase/react-native-firebase/issues/5585)) ([64f569a](https://github.com/invertase/react-native-firebase/commit/64f569acd2cea284baa305451df9533f138539e7))
./packages/app/plugin/__tests__/iosPlugin.test.ts:import fs from 'fs/promises';
./packages/app/plugin/__tests__/androidPlugin.test.ts:import fs from 'fs/promises';
./packages/app/plugin/src/ios/appDelegate.ts:import fs from 'fs/promises';
./packages/perf/plugin/__tests__/androidPlugin.test.ts:import fs from 'fs/promises';

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react-native-firebase – ./

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react-native-firebase-next – ./website_modular

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[codecov]

Codecov Report

Merging #5591 (aaa37d5) into master (90476b8) will increase coverage by 6.74%.
The diff coverage is 33.34%.

❗ Current head aaa37d5 differs from pull request most recent head f2c268f. Consider uploading reports for the commit f2c268f to get more accurate results

@@             Coverage Diff              @@
##             master    #5591      +/-   ##
============================================
+ Coverage     67.36%   74.10%   +6.74%     
============================================
  Files           202      107      -95     
  Lines          9708     4420    -5288     
  Branches       1514      942     -572     
============================================
- Hits           6539     3275    -3264     
+ Misses         2754     1073    -1681     
+ Partials        415       72     -343     

[mikehardy]

Well it's nice to have the fix style confirmed on the android side :-), this should sort it out - thanks @barthap !