[Module Proposal]: `avm/ptn/app/function-app`

### Check for previous/existing GitHub issues/module proposals - [x] I have checked for previous/existing GitHub issues/module proposals. ### Check this module doesn't already exist in the module indexes - [x] I have checked for that this module doesn't already exist in the module indexes. ### Bicep or Terraform? Bicep ### Module Classification? Pattern Module ### Module Name Function App ### Module Details I'm proposing a pattern module for creating Azure Functions including the associated resources needed for successful deployment. For instance, when using Flex Consumption (the current recommended default), you also need: - App Service plan - Storage account - A blob container for deployment - Managed identity (as a way to access the storage account and anything else needed) - Associated role assignments - App Insights - Log Analytics Workspace The WAF-aligned case requires loads of additional stuff as well. To the degree possible, I would like this pattern module to be compatible with using AZD for provisioning and deployment. For example, one way that shows is having ARM tags that apply specifically to the Function App, but none of the other resources created--AZD uses this to map a service in `azure.yaml` to a specific compute resource. Definitely open to suggestions on a better module name. ### Do you want to be the owner of this module? Yes ### Module Owner's GitHub Username (handle) bwateratmsft ### (Optional) Secondary Module Owner's GitHub Username (handle) microsoft/vscodeazuretoolsdev