Add a confirm option to CLI vm create commands which cause downtime

Reference: Feature 4947992: [Linux E2E] Add a confirm option to CLI vm create commands which cause downtime

**Description:**
"If you az vm create with a size, say DS1_v3, and then repeat that same command with DS2_v3 or another size, it changes the VM size. (I was trying to create many instances and forgot to change the -n parameter)

It might be by design, but I wonder if we should warn customers and ask them to add a --yes or something, since it implies downtime. We get that info notice in the portal, not sure if CLI should emit some form of warning.

The RP probably can't do anything unless the "create or update" functionality is split in destructive vs. non-destructive updates. In EC2, there's a "modify instance attribute" method and the VM size can only be changed with a stopped VM."

We already have “az vm resize” so adding some kind of update parameter to destructive creates would make sense.