add manifest schema for workflow file

[Niraj-Kamdar]

[fetsorn]

Right now we are expecting the workflow file to be valid, and we use the Workflow type provided in core-js. We should add support for workflow files to @polywrap/polywrap-manifest-schemas and @polywrap/polywrap-manifest-types-js, and the Workflow type should be imported similar to DeployManifest and InfraManifest. This would validate the workflow file against a json schema, and allow for future migrations of workflow files.