Add a check-all Makefile target

[pquentin]

As mentioned by @dliappis in #1281 (review), it would be useful to do make check-all. It's easy to implement:

check-all: lint test it

But I don't know where to mention it. For example, we don't mention it tests anywhere. (And we probably should, I took some time to understand that those were integration tests.)

Maybe this can be left undocumented, as it is something that only the core team will actually run?

[dliappis]

But I don't know where to mention it. For example, we don't mention it tests anywhere. (And we probably should, I took some time to understand that those were integration tests.)
Maybe this can be left undocumented, as it is something that only the core team will actually run?

We could mention it in the contributor's guide. Right now step 1 is python3 setup.py test but instead it could be to first format the changes and then ensure all tests pass with make check-all.