Added Cop for injecting EE modules

What does this MR do?

This Cop enforces the rule that injecting EE modules (using prepend, include, or extend) is done by placing the injection on the last line of a file, instead of somewhere in the middle. By placing these lines at the very end, merge conflicts will not happen.

What are the relevant issue numbers?

Does this MR meet the acceptance criteria?

• Tests added for this feature/bug
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Security reports checked/validated by reviewer