Release v22.87.0

Added

• QueryScenario can run observable queries backed by Chronicle read models: a query returning IReadModels.Observe<T>(filter) emits the read models built from the scenario's given events and given read models, and emits again when a command in the scenario appends events (#3221) (part of #3154)
• A given read model whose key cannot be read from the instance cannot be observed, and Observe fails with PinnedReadModelCannotBeObserved explaining how to seed it instead (part of #3154)

Changed

• Arc requires Cratis Chronicle 19.54.0 or later (part of #3154)
• In the default scenario mode, observing a read model built with [ChildrenFrom<T>] is not supported yet and fails with Chronicle's error; use decision mode (EnableDecisionReads) for those read models until Cratis/Chronicle#4816 ships (part of #3154)