Understand how to use App Gateway for SCCA

[jrspinella]

Benefit/Result/Outcome
An App Gateway deployment will add additional SCCA control support.

Description

To Do: (additional detail needed in this issue)

• Extensive acceptance standards. Acceptance criteria may be used in place of the information required below. The following scenarios are to be implemented: [Application Gateway Before Firewall] (https://docs.microsoft.com/en-us/azure/architecture/example-scenario/gateway/firewall-application-gateway#application-gateway-before-firewall) or [Application Gateway After Firewall] (https://docs.microsoft.com/en-us/azure/architecture/example-scenario/gateway/firewall (or other scenarios)
• Would AppGW only apply to T3 web application workloads, or does AppGW perform any broader functions for Hub/Spoke?
• The application and usage of service tags, such as "Gateway Manager" and "UDR support" tags.
• List of SCCA controls this configuration addresses

Acceptance Criteria

• A straightforward website is installed behind an ASE ILB.
• All traffic is routed through the application gateway, firewall, and ASE after arriving at a public IP address.
• Traffic is routed to the proper networks using user-defined routes.
• Add deployment assumptions and considerations to the readme.md file