[Module Proposal]: `avm-res-aad-appregistration`

### 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?

Terraform

### Module Classification?

Resource Module

### Module Name

avm-res-aad-appregistration

### Module Details

# Module proposal: Microsoft Entra ID Application Registration

This module aims to simplify the creation and management of Microsoft Entra ID application registrations with Terraform.

Setting up an application today requires combining several `azuread` resources (application, service principal, permissions, etc.), which is often repetitive and implemented differently across projects.

The module would provide a reusable way to handle:
- application registration
- service principal creation
- API permissions (delegated and application)
- app roles
- optional authentication setup (secret or federated identity)

The goal is to make this common pattern easier to use and more consistent across environments.

### Do you want to be the owner of this module?

Yes

### Module Owner's GitHub Username (handle)

Pyodin

### (Optional) Secondary Module Owner's GitHub Username (handle)

_No response_