[rn] Remove the files from react-native-lab, superseded by expo-yarn-workspaces

Move react-native-lab into the Expo repo / directory

Moved react-native-lab into the Expo repo / directory so that RN changes can happen in the client repo. Also found that several parts of react-na

Move react-native-lab into the Expo repo / directory

Moved react-native-lab into the Expo repo / directory so that RN changes can happen in the client repo. Also found that several parts of react-native-lab were unused, like LabConfig.js, so I removed them. There's still some further cleanup we likely can do after tightening up how we do bootstrap-like things in the new repo.

Tested by regenerating the Podfile, running `pod install`, and compiling the iOS app. Also tested that the Android RN upgrade scripts work and the Android app compiles and runs afterwards. Lastly ensured that `expu start` in NCL worked.

fbshipit-source-id: 437513b

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