Allow for custom polling intervals when deploying ARM templates

**Is your feature request related to a problem? Please describe.**
Currently customers who spend a lot of time developing, testing, and debugging ARM templates using the Azure CLI have to wait until the system decides to poll for updates, which might be up to ~30 seconds after the deployment completes. This small delay adds up and is quite frustrating.

**Describe the solution you'd like**
Please consider adding the ability to specify the status polling interval when deploying ARM templates using `az group deployment create`, `az deployment create`, `New-AzResourceGroupDeployment`, and `New-AzDeployment`.

**Additional context**
When deploying ARM templates using the Azure CLI and PowerShell, there is currently no way to specify how frequently the deployment should be polled for updates. There is built-in behaviour that does a semi-exponential backoff, which is a reasonable default behaviour - but in some circumstances (e.g. when deploying and debugging templates interactively) it is preferable to poll for status updates and completion more frequently to avoid wasting time waiting for a polling interval to complete.