Make it easier to run tests

[RalfJung]

Some tests are run by go test, but this is a lot less than what is actually run on CI. It'd be great if go test could somehow be made to test All The Things, or if that is not possible have make test or so that does test All The Things.

Currently, the most convenient way to run tests that I could find is to push to a branch and wait for CI to run...
(The README also doesn't say what to do.)

[tchajed]

make ci and make fix should cover everything in CI.

[RalfJung]

For me, make ci terminates with

./test/bats/bin/bats ./test/goose.bats
make: ./test/bats/bin/bats: No such file or directory

[tchajed]

You just need git submodule update --init --recursive.