Make the User/Client-side Application Golden-Path for Azure.Identity Easy

[joshfree]

Tracking issue for addressing UX feedback on User/Client-side Application "Golden path" scenarios with Azure.Identity. Easy scenarios are still too complicated, require referring to documentation for too many conceptual topics, and it's not clear to new users how best to get started.

This work item tracks adding new simple one-shot or golden-path APIs specific to the User/Client-side Application authentication flows.

[catalinaperalta]

Can this be closed now @joshfree?

[chlowell]

Closing this because there's nothing in it and it's been superseded by other epics