DEBUG ONLY: Enable Core Data assertions. Remove for release

[paulsolt-ofsw]

Enable Core Data assertions with -com.apple.CoreData.ConcurrencyDebug 1 in Debug only.

• We should only merge after beta is finalize to help find invalid Core Data usage.
• IMPORTANT: We need to revert this before a release.
• IMPORTANT: Only merge after we get fixes for: Mage-1690: Core Data Concurrency Debug Fixes #196 (Otherwise we'll get false positives in develop branch)