Add test to cover schema correctness for blocks not used in upstream pipeline configs

[markmc]

We hit #205 after merging #182

@bbrowning suggests we should have a

test that hands a basic yaml block definition to the schema validation for each block type just to ensure baseline expected block configuration is covered by the schemas. I know we have tox -e validate-pipelines, but that only validates the committed pipeline definitions we ship by default as opposed to validating the universe of possible and/or expected possible upstream or downstream pipeline definitions.

[github-actions]

This issue has been automatically marked as stale because it has not had activity within 90 days. It will be automatically closed if no further activity occurs within 30 days.

[bbrowning]

We definitely need better test coverage here, and should try to tackle this as part of upcoming work that will be changing the pipeline definitions, schemas, and yaml.