Revert "Merge branch 'remove-json-schema'"

This puts back the code to check a json schema in resource_type specs.
(#21881) Handle reading the schema ourselves

If we bypass the weird file loading code in json-schema then this works.
Merge branch 'fix-json-validation'

* fix-json-validation:
  (#21881) Handle reading the schema ourselves
  Revert "Merge branch 'remove-json-schema'"