* Enhance PolicyRequestModel and SavePolicyRequest with validation for policy data and metadata.
* Add integration tests for policy updates to validate handling of invalid data types in PolicyRequestModel and SavePolicyRequest.
* Add missing using
* Update PolicyRequestModel for null safety by making Data and ValidateAndSerializePolicyData nullable
* Add integration tests for public PoliciesController to validate handling of invalid data types in policy updates.
* Add PolicyDataValidator class for validating and serializing policy data and metadata based on policy type.
* Refactor PolicyRequestModel, SavePolicyRequest, and PolicyUpdateRequestModel to utilize PolicyDataValidator for data validation and serialization, removing redundant methods and improving code clarity.
* Update PolicyRequestModel and SavePolicyRequest to initialize Data and Metadata properties with empty dictionaries.
* Refactor PolicyDataValidator to remove null checks for input data in validation methods
* Rename test methods in SavePolicyRequestTests to reflect handling of empty data and metadata, and remove null assignments in test cases for improved clarity.
* Enhance error handling in PolicyDataValidator to include field-specific details in BadRequestException messages.
* Enhance PoliciesControllerTests to verify error messages for BadRequest responses by checking for specific field names in the response content.
* refactor: Update PolicyRequestModel and SavePolicyRequest to use nullable dictionaries for Data and Metadata properties; enhance validation methods in PolicyDataValidator to handle null cases.
* test: Add integration tests for handling policies with null data in PoliciesController
* fix: Catch specific JsonException in PolicyDataValidator to improve error handling
* test: Add unit tests for PolicyDataValidator to validate and serialize policy data and metadata
* test: Update PolicyDataValidatorTests to validate organization data ownership metadata
