Expand the list of EC2 instance types for AWS Quickstart Templates

Problem

Currently, the list of EC2 instance types that is allowed to select when creating a CloudFormation stack is hardcoded in the templates such as the one below for Confluence:

• https://github.com/aws-quickstart/quickstart-atlassian-confluence/blob/main/templates/quickstart-confluence-master-with-vpc.template.yaml

Suggestion

Regularly keep the list of available EC2 instance types updated so that the current generation of EC2s are available to select