Set up Azure Front Door for non-prod

[KSchlobohm]

Web-facing traffic should flow through a WAF.

Todo

• [x] remove the boolean surrounding AFD deployment
• [x] modify the createAppRegistration scripts
• update c# code to address AADSTS50011
  • [x] override OnRedirectToIdentityProvider
  • [x] override OnRedirectToIdentityProviderForSignOut
  • [x] create new app config service values AzureAd:FrontDoorPostLogoutRedirectUri & AzureAd:FrontDoorRedirectUri
  • [x] configure asp.net core for proxy
  • [x] update code to explain recommended path of reverseProxy: host name preservation
• [x] update guidance (and template) to explain that we deploy AFD for all environments but that we recommend reusing AFD in real scenarios
• [x] update non-prod estimate