Add option to disable extensions

## Is Your Feature Request Related To A Problem? Please describe.

If someone has an issue with a package automation script not behaving correctly, there is not a good way to ensure that it is not being caused by something in a module from a `.extension` package.

## Describe The Solution. Why is it needed?

A commandline switch could be added to disable loading of PowerShell modules from extensions. This would allow a "blank slate" for the package automation script, to help narrow down what is going on.

## Additional Context.

Discussion should be had around if the licensed extension should be included in this, due to the licensed cmdlets. Potentially it should only be disabled by disabling all licensed functionality with #2774?

## Related Issues

N/A

No files or tests are named. Start by locating command-line option handling and the code that loads PowerShell modules from .extension packages. Clarify whether the licensed extension is included or handled through #2774; done means the option reliably provides a blank slate by preventing the selected extensions from loading.

Written by the indexing model from the issue text.