Update test names and locations

[whoabuddy]

After looking through what we have on feat/migration and feat/migrationplustests, it looks like having the test proposals grouped under the contracts directory will get cluttered very fast.

One idea is to change up the structure so the tests are stored somewhere else, e.g.

contracts <-- only protocol code, no tests
  extensions <-- (ccdNNN)
  external <-- (ccext-)
  proposals <-- (ccip-)
  traits <-- (leave as-is)
tests
  contracts <-- (test proposals)
    test-ccd001-direct-execute-NNN.clar
    test-ccd002-treasury-NNN.clar
    test-ccip012-bootstrap.clar
  extensions <-- (leave as-is)
    ccd001-direct-execute.test.ts

That should scale better, be easier to read, and from there we can start to identify any relevant patterns in the test proposals themselves.

Right now just looking at ccip-test-treasury-006.clar or the newer test-ccd002-treasury-006.clar doesn't tell me much about the test, but we should stick with it for now and look at it alongside #3 for a future refactor.

With fuzzing we could do cool things like setting up the model for what a city looks like it then running the tests on a bunch of different inputs!