Space Invaders uses IL2CPP

[LukeStampfli]

Describe the bug
Space Invaders sample uses IL2CPP backend. When opening with a regular Unity installation without IL2CPP, running it won't work.

To Reproduce
Steps to reproduce the behavior:

1. Download a Unity version, don't check IL2CPP support
2. Open the project.
3. See error

Expected behavior
Our samples should not use IL2CPP and just work if you open them.

Screenshots

Environment (please complete the following information):

• OS: any
• Unity Version: any
• MLAPI Version: 0.1.0
• Bitesize Samples Repository Version/Commit: #5f16e327e83ddcc4e6940947a489607423bb763c

Additional context
Add any other context about the problem here.

[Cosmin-B]

Fixed by PR #10