Use config reader for parsing Job submission

[vishalbollu]

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Description

As of v0.19, job submissions are validated with custom code rather than using the config reader. Config reader wasn't used because it doesn't support json.RawMessage (or just []byte). Update config reader to support []byte or json.RawMessage.

Motivation

• Validation error messages can be improved with the help of config reader
• Remove redundant basic error validations such as min/max checks with the help of config reader

Additional context

• Add a StructFieldValidation for []byte with a parser function to cast to json.RawMessage?