[Monorepo] e2e tests

[dratwas]

Description

This is a part of migration gutenberg-mobile to gutenberg repo.

In this PR I fixed local native e2e tests.
I moved jest_ui.config to the test/native directory.

The tricky part of that is the process.env.MOBILE is set to true in Build Phases -> Bundle React Native Code And Images because react-native/scripts/react-native-xcode.sh always takes babel config from the root - help appreciated with that. I solved it by adding MOBILE env to the Build Phases and if it is set i use the config from packages/react-native-editor

@gziolo left a comment here #18159 (comment)

We need to double-check how Babel caching works with envs.

As far as I understand from here https://babeljs.io/docs/en/config-files#apicache :
the api.cache(true) is an equivalent of api.cache.forever() which means the babel will cache the computed config and never call the function again. So it shouldn't be an issue in that case.

The next thing added here is rn-cli.config.js at the root level which only requires config from packages/react-native-editor. I couldn't make it works w/o this. I tried to set the rn-cli.config.js path as a parameter to react-native/scripts/react-native-xcode.sh w/o adding rn-cli.config.js at the root level.
export BUNDLE_CONFIG=packages/react-native-editor/rn-cli.config.js

Not sure why but in that case I get the error:

Loading dependency graph, done.
error Unable to resolve module `./styles.scss` from /gutenberg/packages/block-editor/src/components/media-placeholder/index.native.js`: The module `./styles.scss` could not be found from `/gutenberg/packages/block-editor/src/components/media-placeholder/index.native.js`. Indeed, none of these files exist:

Seems like the sass-transformer doesn't work correctly.

If you have any idea how to handle those things in a more elegant way please left a comment :)

NOTE: Files from above are only needed for iOS because android works w/o them.

How has this been tested?

npm run native test:e2e:ios:local should start iOS e2e tests and they should pass
npm run native test:e2e:android:local should start android e2e tests and they should pass

Types of changes

Fix native e2e tests

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR. .

[Tug]

Closing as it is now outdated