Update az cli ml to Support for attaching databricks for Azure Machine Learning

[Krisyarr]

az ml compute attach --name databricksattach --resource-group rgname --workspace-name amlworkspace --file "yml file" --type databricks"

Currently az ml compute attach supports only types virtualmachine, Kubernetes.
But existing Databricks cluster cannot be attached using az ml compute attach. Only Solution available is attaching existing Databricks cluster is through the portal and the properties needed for attaching

properties:
databricksAccessToken : xxxxxxxxxxx
workspaceUrl : existingdatabricksworkspaceurl

Need az ml client to support similar to AKS like az ml compute attach --type databricks and its properties in yml

[yonzhan]

Thank you for opening this issue, we will look into it.