Add tracker for unique virtual actions

What does this MR do?

In this MR, we add the new class Gitlab::UsageDataCounters::TrackUniqueActions to track unique user actions to later include them later in the usage ping data.

All the logic comes from the Gitlab::UsageDataCounters::TrackUniqueActions module. This module deals with Event and then translate those into user actions.

What we're doing here is to move that logic into its own tracking action module and the event module will call the other. That way we can reuse the tracking action module for other purposes.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Refs #232824 (closed)