Add stateful-history delta work items to the workflow worker

[JoshVanL]

The sidecar re-sends a workflow instance's entire committed history to the worker on every turn. This adds the worker half of the "stateful history" optimization so that, once a worker is warm for an instance on a work-item stream, the sidecar sends only the new committed events (the delta) and the worker reconstructs the full history from its own cache. It mirrors the Go (durabletask-go), Python, and .NET SDK implementations and is on by default.

Worker (durabletask-client):

• WorkflowHistoryCache: a per-stream cache of each instance's committed history, bounded by a sliding TTL, an instance-count cap, and a byte budget with LRU eviction. Injectable clock for deterministic tests.
• DurableTaskGrpcWorker: advertise WORKER_CAPABILITY_STATEFUL_HISTORY in GetWorkItemsRequest, reset the cache on every reconnect (the sidecar drops the old stream's warm set), and reclaim idle entries with a daemon janitor stopped on close.
• OrchestratorRunner: before replay, resolve the full committed history (cached prefix + delta on a hit, or a GetInstanceHistory fetch on a miss) instead of using the request's pastEvents directly; after replay, cache the committed history, or drop it once the instance ends (a CompleteWorkflow action, covering completed/failed/terminated/continued-as-new). A TerminateWorkflow action targets a different instance and is deliberately not treated as a reset.

Correctness never depends on the cache: any miss (cold stream, eviction, desync) self-heals via the GetInstanceHistory fallback, so this only changes per-turn bandwidth, not results. A fallback fetch that fails abandons the work item for backend redelivery rather than completing with a partial history.

Configuration (DurableTaskGrpcWorkerBuilder):

• disableStatefulHistory to opt out, plus historyCacheTtl, historyCacheMaxInstances, and historyCacheMaxBytes to tune the bounds.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 76.89%. Comparing base (f42e0d2) to head (7a6842a).

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #1777   +/-   ##
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  Coverage     76.89%   76.89%           
  Complexity     2307     2307           
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  Files           244      244           
  Lines          7163     7163           
  Branches        753      753           
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  Hits           5508     5508           
  Misses         1288     1288           
  Partials        367      367           

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