Define Repository Structure

[bruno-garcia]

The current structure is suboptimal. We need to address:

Parts of the repo:

• Unity sample project
• Actual package (installable through UPM (blocks Set up the project for UPM #43)) - needs to be on the root?
  • maybe ~ to ignore some directories we use for dev or samples?
• Folder for source code
• Git submodules
• Add codeowners and issue_template (to indicate Unity version)

...

• Sample project
  • So we can build the .sln and get updated bits into Unity and test it out.
  • Add this project as a sample
  • Delete these unused files

[semuserable]

Closed by #51