feat(tests): add JSON Schema test coverage

[jeremyfiel]

This PR adds schema test coverage for the JSON Schema,

this is based on the work in the OAS and Overlay projects by @MikeRalphson and @ralfhandl

The schema tests do not cover JSON Schema 2020-12 keywords as defined by the inputs keyword. All Arazzo specific keywords are covered by the tests.

I've also included markdownlint-cli to clean up the spec file.

[jeremyfiel]

rebased on v1.0.0-dev to resolve conflicts.

[ralfhandl]

@jeremyfiel Why is the specification markdown source changed by this PR?

[jeremyfiel]

Markdown lint was added and the rebase onto v1.0.0-dev included some recent updates by Frank

I didn't change any wording on it

[ralfhandl]

I would separate these changes into two separate pull requests:

• Markdown formatting
• Schema test coverage

[jeremyfiel]

• stripped out the markdown lint updates
• removed the json version of the schema

[jeremyfiel]

mistakenly removed the original validate-markdown.yaml with mdv checks.

[jeremyfiel]

opps. somehow the validate-markdown.yaml was deleted again. added it back.

it will be replaced and updated by #291 pr after that one is merged.

[frankkilcommins]

Thanks @jeremyfiel - i'm requested changed on the examples to ensure they are valid (which is being fixed for the examples directly in #260 )

Can you also take a look at the merge conflicts?

[jeremyfiel]

tbh, i'm not sure why this is a conflict. the file currently exists on v1.0.0-dev and is requested to be deleted in this PR. so it shouldn't conflict with anything.

[jeremyfiel]

interesting. adding the file back removes the conflict. I can create a separate pr to remove the file after this is merged.. lmk if that works

[jeremyfiel]

taking inspiration from @ralfhandl to update the schema test coverage threshold to 100% like this will not work for this repo because we are not testing the JSON Schema 2020-12 keywords used in inputs. I'm not sure if we want to peg it to ~63% coverage to indicate the threshold is met or not. To be discussed...