Detect changes to PBXProject-wise build settings during target build up-to-date checking

[lacasseio]

As a user building Xcode targets using Gradle, I want the Gradle task representing the Xcode target to be out-of-date during an incremental build when the project's build settings change so I can have accurate feedback.

Acceptance Criteria

• Changes to build settings (add, remove, modify) on PBXProject for the specified configuration cause the task to be out-of-date.