add RNTester-E2E: tests for iOS and Android via Appium, WDIO and Jest (#36267)

Summary:
The motivation is to create an E2E testing solution for the RNTester app that can be used to flag when things break and the release crew can use to validate more of the codebase ahead of a release.

This first PR wants to just showcase the main flow (how tests are made, where the E2E folder lives, how it's used by CircleCI) and then we can build on top of it with subsequent PRs, with the help of an umbrella issue to get the community involved in making more tests!

This work is being done cooperation with Callstack developers (mateuszm22 , adzironman, and others) - reason why the branch [lives in a fork](https://github.com/mateuszm22/react-native/tree/k%2Bm/new-rn-tester-E2E).

### [Read the RFC for more details ](https://github.com/react-native-community/discussions-and-proposals/pull/684)

### Extra notes

We are still on WebDriverIO 7 because during the exploratory phase, WDIO was a bit problematic and the workarounds needed to make it work don't seem very nice - see this PR: https://github.com/kelset/react-native-e2e-jest-appium-webdriverio/pull/4 --- this will be revisited in the future, once there's a better path for upgrading.

### Things that will be handled as follow up work

* upgrade to WDIO 8
* [an automated yarn run-e2e-test script](https://github.com/facebook/react-native/pull/36267#discussion_r1269378065)
* [a small refactoring into a js script](https://github.com/facebook/react-native/pull/36267#discussion_r1272050735)

## Changelog:

[INTERNAL] [ADDED] - Added first working configuration for e2e testing

Pull Request resolved: https://github.com/facebook/react-native/pull/36267

Test Plan:
You can play with this locally by [follow the readme](https://github.com/mateuszm22/react-native/blob/k+m/new-rn-tester-E2E/packages/rn-tester-e2e/README.md).

CircleCI jobs will be added.

Reviewed By: cipolleschi

Differential Revision: D47763012

Pulled By: cortinico

fbshipit-source-id: 6eb9674182b8ee97aea4784158c69bf017f379e5