Make Ci::Minutes::Notification user agnostic

What does this MR do?

Related to #213964 (closed)

Currently Ci::Minutes::Notification holds information about notification levels. We could reuse this class in other aspects of Ci::Minutes if it wasn't for its coupling with current_user in order to display or not a notification.

By removing current_user in Notification, and instead passing it as parameter to show? method, we can reuse it as a ValueObject in other contexts and make it also a SSOT for notification levels.

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
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