Extensibility tests: Algorithm and Signature - JWT, SAML and SAML2

[iNinja]

Extensibility tests: Algorithm and Signature - JWT, SAML and SAML2

• Added SecurityTokenInvalidOperationException to replace InvalidOperationException when used with ValidationError subclasses
• Added SignatureValidationError to handle exceptions generated during
• Removed XmlValidationError. Updated XML signature validation to use SignatureValidationError instead
• Removed nullability from signature validation delegate's CallContext
• Added log messages and validation failure types for the exception throwing
• Handle potential exceptions thrown during signature validation (both signature and algorithm)
• Updated validation errors
• Added custom validation errors and delegates for algorithm and signature validation
• Added algorithm extensibility tests for JWT, SAML, and SAML2
• Added signature extensibility tests for JWT, SAML, and SAML2

Part of #2711