Add skeleton to enable Durable cmdlet development

[michaelpeng36]

This PR is one of four that will sync the main branch with the changes made in the michaelpeng/refactoring-engine branch.

1. https://github.com/Azure/azure-functions-durable-powershell-private/pull/18
2. https://github.com/Azure/azure-functions-durable-powershell-private/pull/19
3. https://github.com/Azure/azure-functions-durable-powershell-private/pull/20
4. https://github.com/Azure/azure-functions-durable-powershell-private/pull/21

All the changes in the PRs listed were co-authored with equal contribution from @davidmrdavid. This change in particular adds basic changes necessary to begin Durable cmdlet development, including:

• The SharedMemory structure to coordinate switching between the invoker and the user-code threads
• The OrchestrationContext structure to represent data needed by the orchestration to proceed,
• The SetFunctionInvocationContextCommand and OrchestrationInvoker classes to pass data to and from the PowerShell worker to invoke the orchestration.
• Utility classes to ensure the above compile