Add SDK to integrate with MAUI on iOS, macOS and Android

[frederikprijck]

Changes

Initial implementation for supporting MAUI.

This supports integrating Auth0 in MAUI applications that target iOS, macOS and Android.

Windows support will be investigated and, if possible, supported through a follow up PR.

Testing

Please describe how this can be tested by reviewers. Be specific about anything not tested and reasons why. If this library has unit and/or integration testing, tests should be added for new functionality and existing tests should complete without errors.

• [ ] This change adds unit test coverage
• [ ] This change adds integration test coverage
• [x] This change has been tested on the latest version of the platform/language or why not

Checklist

• [x] I have read the Auth0 general contribution guidelines
• [x] I have read the Auth0 Code of Conduct
• [x] All existing and new tests complete without errors
• [x] All code guidelines in the CONTRIBUTING documentation have been run/followed