[Feature]: Check for presence of AzureRM on load of Az.Accounts

### Description of the new feature

When importing Az.Account, can we detect if any of the AzureRM modules are already installed and through an actionable error message with a pointer to docs how to handle the situation?

### Proposed implementation details (optional)

We could use "ScriptsToProcess" on Az.Accounts to perform this validation.
cc: @mikefrobbins

Start at the Az.Accounts import path and inspect how its ScriptsToProcess mechanism could perform the requested validation. Reproduce the case where AzureRM modules are installed, then verify that importing Az.Accounts produces an actionable error with a documentation pointer.

Written by the indexing model from the issue text.