Check for permissions before starting deploy or undeploy in Azure

As a user, I want to be sure that I have enough permissions required by HubCTL in Azure before starting deploy or undeploy operations with the `hubctl stack` extension (probably other extensions too).

A possible solution is to add logic to `init` or `configure` extensions that check permissions.

- [ ] Define a list of Azure permissions required by HubCTL
- [ ] Implement checking logic
- [ ] Document required Azure permissions in hubctl.io

Start with the `hubctl stack` extension and inspect its `init` and `configure` entry points, since no files or tests are named. Define the Azure permissions required by HubCTL, check them before deploy and undeploy operations, and document the requirements in hubctl.io.

Written by the indexing model from the issue text.