CAIP-25: The specification must describe how to handle successive CAIP-25 requests

[rekmarks]

Ref: #138

Problem

Once a CAIP-25 request has succeeded, nothing stops the dapp from making successive CAIP-25 requests with different methods, events, chains, and namespaces. For completeness, the specification needs to specify what happens when successive CAIP-25 requests are made. In addition, it could be useful to permit the following operations:

• Terminating an existing handshake
• Updating an existing handshake with new methods, events, chains, or namespaces