Update profile.ps1 template to show how to enable the new external Durable Functions PS SDK

In the near future, the PowerShell Azure Functions team will be releasing a new standalone Durable Functions SDK for PowerShell.

After installing it from the PowerShell Gallery, users need to enable it by explicitly importing the package in their profile.ps1. We should update our profile.ps1 templates so that customers have a guide on how to do this.

This will most likely just be a commented out import statement such as Import-Module AzureFunctions.PowerShell.Durable.SDK at the end of [the file](https://github.com/Azure/azure-functions-host/blob/dev/src/WebJobs.Script/FileProvisioning/PowerShell/profile.ps1).

Note that we do not need to complete this task until a public announcement is made for the new SDK. In the meantime, this ticket simply exists to track that work. I will submit the PR for it once we're ready.