[Validator] Reference the objects directly instead of querying using field names

[wakaztahir]

• Deprecate methods that use unchecked casts to validate schema using string fields by using overlays , With a ReplaceWith that would replace the function call to its Validator
• Replace all the function calls using ReplaceWith
• Check where the constant fields of Impl classes are being used and delete them if unused
• Change Impl code to not generate unused constant fields in companion objects