[Feat]: Introduce server call context into the task store interface

[pstephengoogle]

Is your feature request related to a problem? Please describe.

In production systems the persistence of the task should be protected based on the credentials of the creator of the task (e.g. a user id or email). Additionally, applications may have other criteria to use for task persistence (like application name, or region task runs in).

Describe the solution you'd like

Providing the ServerCallContext into the calls to the get, save and delete interface for the task store allows customization of the persisted task data based on the characteristics needed for a real solution. Agent implementors can construct the appropriate ServerCallContext based on the incoming request and use that information at task creation, retrieval and deletion time.

Describe alternatives you've considered

No response

Additional context

No response

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