Support new API fields in ActivityHandle.describe

CHANGELOG.md

@@ -20,6 +20,9 @@ to include examples, links to docs, or any other relevant information.
 
 ### Added
 
+- Added new options to ActivityHandle.describe() to retrieve associated payloads, such as activity input and outcome.
+- New properties and methods in ActivityExecution and ActivityExecutionDescription.
+
 ### Changed
 
 - System Nexus Signal-with-Start Workflow operations now use the typed
@@ -37,6 +40,14 @@ to include examples, links to docs, or any other relevant information.
   `StorageDriverSelectContext` instead of a `StorageDriverStoreContext`. Update the annotation;
   the new type carries the same `target` field. Since selectors are plain callables, a stale
   annotation fails type checking rather than at runtime.
+- `client.ActivityExecution` and `client.ActivityExecutionDescription` had some fields removed or renamed
+  to match RPC API.
+  - Dataclass parameters for these types were changed to `frozen=True, eq=False, kw_only=True`.
+  - `scheduled_time` was renamed `schedule_time`.
+  - `last_failure` was changed from field to method that runs data converter on demand.
+  - `state_transition_count`, `eager_execution_requested`, `paused` and `long_poll_token`  were removed.
+- ActivityHandle.describe() long-poll token was removed.  The functionality can still be used manually
+  through raw gRPC API.
 
 ### Fixed