Enhance schema files to prevent schema validation issues

[elyra-ai]

Enhance schema files to prevent schema validation issues

[cindyzh-ibm]

@tomlyn Thanks a lot for reviewing and approved the PR.

[tomlyn]

@cindyzh-ibm I know is a separate thread for this issue you said you had used “JSON schema validation tools.” that had caused errors with the current schema files. What are they?

In common canvas we use jsonschema to validate incoming and outgoing pipelineFlow and palette documents and that doesn’t have any problems with the current pipleine-flow-v3-schema.json and pipeline-flow-ui-v3-schema.json files.

If we make changes to the schema files we'll have to make sure it doesn't break anything in common-canvas.

[cindyzh-ibm]

Java Json Tool library https://github.com/java-json-tools/json-schema-validator
networknt library: https://github.com/networknt/json-schema-validator

Both of them use Jackson JSON

[tomlyn]

Changes from PR merged.