feat: Add protocol version negotiation

Implement protocol version negotiation between MCP client and server to ensure
compatibility and graceful version handling.
The server will now suggest the latest supported version when an
unsupported version is requested, while the client will verify
version compatibility during initialization.

- Support multiple protocol versions in both client and server
- Negotiate compatible version during initialization
- Fall back to latest version when unsupported version requested
- Add comprehensive test coverage for version negotiation

Resolves #71

Signed-off-by: Christian Tzolov <christian.tzolov@broadcom.com>