Add Eternity Engine

[d10sfan]

New Engine Package Submissions

• Have you followed the instructions in the build documentation?
• Have you run the build locally and ensured the package allowed you to launch and play the Steam game?
• Have you updated the packages.json file?
• Have you ensured that there is not already a pull request or active engine package for the one you are adding?

Common Code Submissions

• Have you verified that the changes are isolated to the features or fixes you are wanting to do?
• Have you tested at least one of the engines to ensure that your changes do not break existing workflow?
• Have you described what your changes are accomplishing?