Improve settings form

The name field should have a description that explains what it is used for.

The endpoints and secrets fields should be required, because without them you can't connect with Azure

The User info endpoint configuration should default to MS Graph API because that is default nowadays

Review the description help text to see if they are as clear as possible.

Compare labels with Azure to ensure we use the same terminology (for example Client ID is called Application ID in Azure)

Add links to drupal.org documentation