MapsToCook is not relative and is ignored if the project's directory is moved

If the MapsToCook is set in the editor using the "List of maps to include in a packaged build" and the project's directory is moved, the list is no longer valid as it was pointing to the specific file path for those maps.

1. Create a new blueprint project
2. Create two new maps and save the entire project
3. Open Edit > Project Settings > Packaging and extend the options via the arrow at the bottom.
4. Find the field entitled "List of maps to include in a packaged build" and add elements to set the maps from earlier until all are set.
5. Find the "Use Pak File" option and make sure it is unchecked
6. Save the project and move the project's directory to another location on your computer (Do not copy or the path will still exist and the bug will not reproduce)
7. Reopen the project and select File > Cook Content for Windows
8. Once the cook is complete, check the file directory for Saved > Cooked > WindowsNoEditor > ProjectName > Content
   Result: No content folder exists at this directory unless other items were cooked. The maps were not cooked.
   Expected: The cooked maps should be listed at this directory.