[Feature] [Application Gateway for Containers] Support alias records on Azure DNS zones

**Is your feature request related to a problem? Please describe.**
Currently there seems to be no supported way to use Application Gateway for containers on apex records on domains (due to cname not being supported on apex records)? Unless it is supported/recommended to use A record to link the apex domain to the anycast IP address in use?

Might be on a roadmap already, but it seems getting support wit the Azure DNS zone alias record set would be helpful to allow me to use apex records? This would also be helpful to avoid dangling DNS records for customers?

Optional: Set the appropriate GitHub label(s) to indicate the AKS feature or area your feature request relates to.
app-gateway-for-containers

**Describe the solution you'd like**
Having the Application Gateway for Container frontend available as choice for alias record set same as other similar resources.

**Describe alternatives you've considered**
N/A

**Additional context**
N/A