Quote "$NODE_BINARY" in react-native-xcode.sh (#21383)

Summary:
Fix build errors when path to $NODE_BINARY contains spaces:

error: Can't find '/Path/With Spaces/To/node' binary to build React Native bundle

Why would $NODE_BINARY contain spaces? In my case, I am using sentry-cli which wraps the NODE_BINARY in it's own executable. The local path to the project, and thus the $NODE_BINARY, contains a space on my GoCD build agent.

'/Users/go/Library/Application Support/Go Agent/pipelines/my-ios-app/node_modules/sentry/cli/sentry-cli

See https://github.com/getsentry/react-native-sentry/issues/484 https://github.com/getsentry/react-native-sentry/issues/389
Pull Request resolved: https://github.com/facebook/react-native/pull/21383

Differential Revision: D10851141

Pulled By: yungsters

fbshipit-source-id: f46853ac8b57957864e0d1a76b8513403223fccb