Move universe tests to universe dir

[shykes]

Extract (some*) universe tests from the dagger integration tests, into their own test suite.

Pros:

• Dogfooding: use dagger to develop universe. Discover exciting new bugs and UX limitations!
• Learning: deep dive into integration tests is a great way to better understand the beast
• Scale: universe will grow faster than dagger core: more packages, more people, more tests. The sooner we separate testing infra, the sooner we can prepare for the tsunami.
• Simplify: slowing or even stopping growth of core integration tests will make it easier to refactor them.
• Unify: Test data now lives within the package

Cons:

• Dagger UX makes workflow a bit awkward (but at least now we can fix!)
• Some duplication between universe and tests/stdlib
• Not all tests are ported: only those with a ready-to-use env

Please keep an open mind when weighing pros vs cons! If you are on the fence about merging, please consider a mercy “checkpoint merge” + improvement requests, to spare me the pain of manual rebase on new tests 😭

My hope is that we can use this as a starting point, then gradually use dagger more and more, and ideally replace yarn & make with dagger completely.

[shykes]

cc @TomChv to make sure your docker run tests survived the transition. Let me know if you see anything strange

[aluzzardi]

LGTM

The tests/ stuff predates gitflow and was awkwardly ported over in a rush (i.e those were the tests we needed, not the ones we deserved).