[enhancement]: Support fastjsonschema as well as jsonschema for schema validator

[ani-sinha]

Enhancement

In RHEL, we are looking to drop support for jsonschema. We would like to use fastjsonschema. The api doc is here: https://horejsek.github.io/python-fastjsonschema/

It would be nice if cloud-init could support both python libraries to check json schema.