Add temp_compute_name Packer Build Variable to Templates

[egg-r]

Could the "temp_compute_name" Packer build variable be added to the Ubuntu/Windows templates? This would be a similar or almost identical setup as the variable temp_resource_group_name. I'm trying to get around our Azure Naming convention policies is why, and to better name the temp VM resource that's created.

https://developer.hashicorp.com/packer/plugins/builders/azure/arm#temp_compute_name