Upgrade wagon and add tests

[silasdavis]

edit: oops I missed this: https://github.com/perlin-network/life/pull/89/files. I think the tests still have value so I can rebase once #89 is merged if you want to accept these changes

This helps alleviate a lot of downstream pain with replace directives needed for transitive wagon dep.

I also found it slightly painful to run tests so I have added a makefile and also a github actions config. To enable this you would need to join the github actions beta here: https://github.com/features/actions

Makefiles are a little arcane, but they are quite standard in Go and I feel like a better tool for the job than the current python script. Let me know if you think that script could be removed or if you want me to tweak the makefile approach.

I've added the test suite as a git submodule so make test will now generate wast and run tests provided you have wast2json on your path.

[silasdavis]

We could avoid the strings in this switch if upstream merges: go-interpreter/wagon#172

[iwasaki-kenta]

Agreed; I left a suggestion comment over in go-interpreter/wagon#172. It's not absolutely mandatory, though regardless of whichever option is chosen for converting an opcode into a string, we should definitely incorporate the change int a separate PR.

[iwasaki-kenta]

Thanks a lot for the PR! Merged in #89 just recently; would love to start incorporating tests into the CI cycle. Let me know when you're able to rebase and then LGTM.

Happy with the Makefile approach, which is what we take for other projects we have in the organization.