Improve License Compliance navigation

Move navigation items in the global navigation

• Move the deprecated product features to the bottom of the navigation section.
• Add (deprecated) to the navigation items of deprecated features (to comply with step 4 at https://docs.gitlab.com/ee/development/documentation/versions.html#deprecate-a-page-or-topic).
• Move the "SPDX license list import" topic as it's a child topic of the "License List" topic.