Merge pull request #7333 from piwik/7276_update_command_progress

Fixes #7276 display update progress in core:archive command. Includes Updater refactor: deprecate static methods in Updates in favor of instance methods that are passed an Updater instance, use instance methods in Updater, move methods in CoreUpdater that perform updates to Updater class, add observer class that can be used within Updater to hook into single updater run.