Early warning if ADO extensions aren't installed

**Is your feature request related to a problem? Please describe.**
If the required extensions aren't installed, the generator will attempt to do so. If the user does not have the required permissions, this will fail the entire (sub)generation process.

**Describe the solution you'd like**
After the ADO details have been entered (org and pac), the existence of extensions can be checked, and if the user doesn't have permissions, notify the user and quit the process.

Start by locating the generator entry point where ADO organization and PAC details are entered, then trace the extension installation path used during the generation or subgeneration process. Determine where extension availability and permissions can be checked before installation; done means users without permission are notified and the process exits before generation fails.

Written by the indexing model from the issue text.