Lint is failing with some inscrutable panic (on a commit with no code
changes). Let's try bumping the version in case they fixed it.
Additionally, the new version's github action uses Go 1.19, which means
it pulls in gofmt updates to match the new [doc-comment formatting rules][1].
So I added Go 1.19 to our list of versions to test (fixes#216)
and updated some of our doc-comments to format better in the
new world (mostly using the new link syntax).
[1]: https://go.dev/doc/comment
Test plan: make lint
Multiple schema-files are now supported as of #134, but the support was
a bit different from how we did multiple operation-files. Before anyone
starts to depend on the ways the syntaxes differ, let's just make them
the same. Since it's easy, I also added support for having just a
single operations-file.
I also realized while writing this that the type-change is technically
breaking (if you call from Go), so documented it as such. I think
this is unlikely to affect many people.
Test plan: make check
Ben Kraft