Feature request: register a resource provider used in subnet delegation even if no resource in that RP is being created by the template

[nzthiago]

With Azure Functions Flex Consumption we have an interesting situation. For the Virtual Network Integration feature to work, the subnet delegation needs to be against Microsoft.App/subnet to work. But the function app's RP is Microsoft.Web.

This means in a bicep like this, there's no actual resource being created by the bicep against Microsoft.Web but there is a subnet delegation against it.

RP registrations seem to already happen according to this documentation, so this is a request for Bicep to also consider subnet delegations when auto-registering RPs.