eliminate loose code in ucm

[aryairani]

• [ ] support forking code between projects/branches; currently loose code is used for that
• [ ] move it to a project
• [ ] update the docs / tutorials
• [ ] root branch implications

Seems like we should focus on supporting project workflows before putting energy into removing loose code? Does leaving it as-is slow us down somehow?

• [ ] What about loose code on Share?
  • [ ] someone may depend on unmigrated share loose code
  • [ ] what about exercism?

[ceedubs]

Some use-cases that I think need to be addressed before eliminating loose code:

• 4253

• 4423