* Upgrade to .NET 10
- Require .NET 10 SDK
- Include net10.0 assets in all assemblies
- Move net9.0-only targets to net10.0
- Update LangVersion to latest
- Remove complicated distinctions between debug target TFMs and release target TFMs
- Remove unnecessary package dependencies when built into netcoreapp
- Clean up some ifdefs
- Clean up some analyzer warnings
* Fix CI
* refactor: remove unused internals
* feat: Execution Mode for sharing a workflow among concurrent runs
* feat: Update WorkflowHostAgent to support concurrent execution
* Also update AsAgent APIs to support injecting a CheckpointManager and an IWorkflowExecutionEnvironment
* fix: Make Read logic consistent in DeclarativeWorkflowContext