SK-1829 Fix http status for validation errors in Java SDK v2

[skyflow-vivek]

This PR adds an enum for default Http status in validation errors thrown by Java SDK. It also fixes issues in invoke connection flow for outbound connections.

Why

• Added default Http status for SDK side validation errors.
• Fixed outbound connection flow for invoke connection.
• Fixed error handling in invoke connection.

Goal

• Will add default Http status for SDK side validation errors.
• Will remove issues with invoke connection flow.
• Will help in reducing inconsistencies and failures in E2E tests.

Testing

• Fixed failing test cases due to this changes introduced.
• Covered the newly added enum in unit tests.