In templates, have option to override pre-tag name instead of using Resource Group name

[Badgerati]

When VMs, NIC/VNETs, etc. are all created, the default naming scheme is:

<resource_group_name>-<tag>[-nic/-vnet]

This is useful, but if the Resource Group name is long, or would look cluttered in the above format, then it's hardly ideal.

This issue is to introduce a parameter into the template files of "pretag", which if present will override the usage of the Resource Group name being used in all resource creation:

<pretag>-<tag>[-nic/-vnet]

This means, that if your group name were "test-web-rg" and you wanted a VM with tag "web", you'd get "test-web-web1" which looks a little silly. Whereas if you set the pretag to be "test" then you'd have "test-web1" which looks a little better!