Add RG, App registration and Service Principal creation option for complete setups from scratch

[luis261]

Currently, running create-py-function-app.ps1 requires you to have already created a Resource Group with a corresponding App registration in AAD as well as a Service Principal (with Contributor access to that group) used for the automated deployments from Azure DevOps via the Service Connection.

The reason for that is that at my day job where I prototyped this tool, AAD access is (understandably) reserved only for the Azure team, which leaves me without any way to automatically handle that part via the CLI. I figured that the same might be true for a lot of other organizations ..

However, I will probably end up implementing an option for fully automated RG setup anyway, especially if enough people ask for it.

https://learn.microsoft.com/en-us/cli/azure/group?view=azure-cli-latest#az-group-create

https://learn.microsoft.com/de-de/cli/azure/ad/app?view=azure-cli-latest#az-ad-app-create
https://learn.microsoft.com/en-us/cli/azure/ad/sp?view=azure-cli-latest#az-ad-sp-create-for-rbac
https://learn.microsoft.com/en-us/cli/azure/role/assignment?view=azure-cli-latest#az-role-assignment-create (not needed if using integrated role assignment params via az-ad-sp-create-for-rbac)