[PM-26429] Add validation to policy data and metadata (#6460)

* 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

src/Core/AdminConsole/Utilities/PolicyDataValidator.cs

@@ -0,0 +1,81 @@
+using System.Text.Json;
+using Bit.Core.AdminConsole.Enums;
+using Bit.Core.AdminConsole.Models.Data.Organizations.Policies;
+using Bit.Core.AdminConsole.OrganizationFeatures.Policies.Models;
+using Bit.Core.Exceptions;
+using Bit.Core.Utilities;
+
+namespace Bit.Core.AdminConsole.Utilities;
+
+public static class PolicyDataValidator
+{
+    /// <summary>
+    /// Validates and serializes policy data based on the policy type.
+    /// </summary>
+    /// <param name="data">The policy data to validate</param>
+    /// <param name="policyType">The type of policy</param>
+    /// <returns>Serialized JSON string if data is valid, null if data is null or empty</returns>
+    /// <exception cref="BadRequestException">Thrown when data validation fails</exception>
+    public static string? ValidateAndSerialize(Dictionary<string, object>? data, PolicyType policyType)
+    {
+        if (data == null || data.Count == 0)
+        {
+            return null;
+        }
+
+        try
+        {
+            var json = JsonSerializer.Serialize(data);
+
+            switch (policyType)
+            {
+                case PolicyType.MasterPassword:
+                    CoreHelpers.LoadClassFromJsonData<MasterPasswordPolicyData>(json);
+                    break;
+                case PolicyType.SendOptions:
+                    CoreHelpers.LoadClassFromJsonData<SendOptionsPolicyData>(json);
+                    break;
+                case PolicyType.ResetPassword:
+                    CoreHelpers.LoadClassFromJsonData<ResetPasswordDataModel>(json);
+                    break;
+            }
+
+            return json;
+        }
+        catch (JsonException ex)
+        {
+            var fieldInfo = !string.IsNullOrEmpty(ex.Path) ? $": field '{ex.Path}' has invalid type" : "";
+            throw new BadRequestException($"Invalid data for {policyType} policy{fieldInfo}.");
+        }
+    }
+
+    /// <summary>
+    /// Validates and deserializes policy metadata based on the policy type.
+    /// </summary>
+    /// <param name="metadata">The policy metadata to validate</param>
+    /// <param name="policyType">The type of policy</param>
+    /// <returns>Deserialized metadata model, or EmptyMetadataModel if metadata is null, empty, or validation fails</returns>
+    public static IPolicyMetadataModel ValidateAndDeserializeMetadata(Dictionary<string, object>? metadata, PolicyType policyType)
+    {
+        if (metadata == null || metadata.Count == 0)
+        {
+            return new EmptyMetadataModel();
+        }
+
+        try
+        {
+            var json = JsonSerializer.Serialize(metadata);
+
+            return policyType switch
+            {
+                PolicyType.OrganizationDataOwnership =>
+                    CoreHelpers.LoadClassFromJsonData<OrganizationModelOwnershipPolicyModel>(json),
+                _ => new EmptyMetadataModel()
+            };
+        }
+        catch (JsonException)
+        {
+            return new EmptyMetadataModel();
+        }
+    }
+}