Deployment spack.yaml schema versioning

[aidanheerdegen]

Currently the version of the spack.yaml schema is defined in a repo variable SPACK_YAML_SCHEMA_VERSION.

If there is an interdependence between code and CD workflows does it make sense to specify the schema version as part of the workflow and it's associated version?

[aidanheerdegen]

With the intention of moving to CI2.0 and adopting similar design patterns to CD now might be there right time to consider this.

[CodeGat]

The only issue with making it code based is having to rebase pull requests every time it changes, messing up the history/comments in PRs.

[CodeGat]

I think this would be a good change to get in (adding a inputs.spack-yaml-schema-version), bundled with a new inputs.spack-yaml-schema-path.

Should there be a default inputs.spack-yaml-schema-version (like latest or something), or should it always be specified? I suppose to keep it in line with the existing vars.SPACK_YAML_SCHEMA_VERSION, it should be explicit.