Handle resource group names with issues like uppercase letters

[bwoolf1]

The resource group name for a Dev Tools environment is used as the prefix for naming Kubernetes resources, so the resource group name has to follow the restrictions for Kubernetes resource names. Either the script should warn the user at the beginning that the resource group name won't work, or better yet, when the script sets the prefix based on the resource group name, it should fix problems in the name such as converting capital letters to lowercase, converting underscores (and spaces?) to dashes, etc. That way the prefix is always a valid Kubernetes resource name even if the resource group name is not.