* Implement Alteration types and engine
* Implement Alteration APIs
* Refactor activity work item with support for activity input
* Serialize scheduled activities as part of workflow state
* Add signal to schedule child activity
* Implement stores for plans and jobs
* Add EF Core provider
* Add Retry endpoint
* Keep root context as always active. The root context is the workflow execution context and contains persistent variable state
* Regenerate EF Core migrations
* Handle orphaned activity execution contexts
* Refactor workflow execution factory
* Enable configuring Jint from Program
* Update ModifyVariable alteration with support for type deserialization
* Use ShortGuid for identity
* Cleanup WorkflowServer host
