Summary:
Fixes an issue with installing third party on iOS when the project's path contains a space, no matter where the space is in the path.
__Error__
```
/Users/AwesomeUser/Library/Developer/Xcode/DerivedData/AwesomeProject-xxx/Build/Intermediates.noindex/React.build/Debug-iphoneos/double-conversion.build/Script-190EE32F1E6A43DE00A8543A.sh: line 3: /Users/AwesomeUser/path contain space/scripts/ios-install-third-party.sh: No such file or directory
/Users/AwesomeUser/Library/Developer/Xcode/DerivedData/AwesomeProject-xxx/Build/Intermediates.noindex/React.build/Debug-iphoneos/double-conversion.build/Script-190EE32F1E6A43DE00A8543A.sh: line 3: exec: /Users/AwesomeUser/path contain space/scripts/ios-install-third-party.sh: cannot execute: No such file or directory
```
Closes https://github.com/facebook/react-native/pull/15377
Differential Revision: D5572671
Pulled By: shergin
fbshipit-source-id: 102727fc1b820e399e170c9c0cb73fd5d1e018d5
95d5d112ac