dev - Added hook to allow other plugins to provide their own authenti…

[iugo-robert]

Description

Added a filter to the user object to allow other plugins to provide their own authentication methods. This change introduces a new filter duo_universal_authenticated_user which can be used to modify the authenticated user object or handle authentication in a custom way.

Motivation and Context

This change is required to provide flexibility in the authentication process, allowing other plugins to hook into the authentication flow and provide their own methods. It solves the problem of rigid authentication by enabling extensibility through WordPress filters.

How Has This Been Tested?

• Verified that the filter duo_universal_authenticated_user is applied correctly during the authentication process.
• Tested with a custom plugin to ensure it can modify the user object as expected.
• Ensured that the default authentication process remains unaffected when no custom plugins are hooked into the filter.

Types of Changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)