Schema validation fails before the `${{env.*}}` parameters have been removed

[vordimous]

Describe the bug
the json schema does not check for the presence of env variables ${{env.*}} in the zilla.yaml and invalidates fields that aren't expecting strings.

To Reproduce
Steps to reproduce the behavior:

1. open a zilla.yaml in vscode with ${{env.*}} defined in a number field and it will have an error shown

[jfallows]

We need to programmatically annotate the zilla schema to explicitly support ${{...}} expression strings for all object property values, whether string or not, and check this schema first on the input config text.

We should also show this annotated schema when verbose schema config is set, so we can output it and use it for VS Code.

Then we should validate using the original (non-annotated) schema after replacing the ${{env...}} expressions with environment variable values, to make sure the replaced values still honor the schema.