Add Support for custom attributes

[Avinash-Kamath]

Issue

IDP like OKTA, Azure support custom attributes along with scim attributes. Today Resource type validations will drop all non-scim compliant attributes during validation

Solution

Adding a flag to allow non-SCIM compliant attributes, updating the validation logic to include these attributes

Support for custom attributes:

• resource_type.go: Added AllowNonScimKeys flag to ResourceType to allow non-SCIM compliant attributes. Updated the validate method to include these attributes in the resource type. [1] [2]

Testing enhancements:

• handlers_test.go: Added the AllowNonScimKeys flag to the newTestServer function and created a new test TestServerResourceHandlerWithCustomAttributes to verify the handling of custom attributes. [1] [2]
• utils_test.go: Added a helper function assertEqualMaps to compare maps in tests.