feat: added method value validation and more strickt restriction on const values

[hashemix]

📌 Summary

This pull request introduces enhancements to the schema by adding more restrictions and validation for constant values in structs and enums, ensuring stricter data integrity during serialization and deserialization.

Additionally, new unit tests have been implemented to verify the correctness of these changes, including serialization/deserialization cycles, custom deserializer validation, and edge cases.

🔍 Related Issues

• Fixes Should we enforce the validation for method field in xxxRequest? #75

✨ Changes Made

• Added custom deserialization logic to enforce constant values for fields like method in structs such as CallToolRequest, CancelledNotification, etc.
• New unit tests to verify the correctness of these changes, including serialization/deserialization cycles, custom deserializer validation

🛠️ Testing Steps

run:

./scripts/run_test.sh