[expo-dev-menu][ios] Prevent registering multiple root views (#10050)

# Why

`RCTRootView` assumes it is created on a loading bridge. In our fork, the bridge has usually already loaded. So we manu

[expo-dev-menu][ios] Prevent registering multiple root views (#10050)

# Why

`RCTRootView` assumes it is created on a loading bridge. In our fork, the bridge has usually already loaded. So we manually create `RCTRootView` when we want to display the application. However, it doesn't work with the original RN.

# How

Made `bundleFinishedLoading` an empty function to not start the application here:
https://github.com/facebook/react-native/blob/f0e80ae2292ebf7ce32666900007845724844fb5/React/Base/RCTRootView.m#L101-L103

# Test Plan

- bare-expo ✅
- using a vanilla app - https://github.com/tcdavis/dev-menu-test ✅

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