add option to return id and name in down level logon name format

[mathew-pigram]

Description

Allow users to specify the required format of the returned id and name. Defaults to logonName. Setting the option 'downLevelLogonName' to a truthy value will return the id and name in down-level logon name format

References

Issue #49

Testing

current functionality and defaults remain unaffected. Setting a new option 'downLevelLogoName' to a truthy value will return the id and name in downLevelLogonName format.

Unit tests have been added to tests/validations.tests.js

• This change adds test coverage for new/changed/fixed functionality

Checklist

• I have added documentation for new/changed functionality in this PR or in auth0.com/docs
• All active GitHub checks for tests, formatting, and security are passing
• The correct base branch is being used, if not the default branch