Auditing of changes to project tags

Description

Project tags are a great way to categorise projects. For on-premise installations, this is especially strong as it can be used in combination with custom added functionality using git hooks; using tags is a simple way to enable or disable such custom functionality.

For use like this, it would be great to have auditing on the tags. That way, enabling/disabling of important functionality can be monitored and traced.

Proposal

Add auditing for the project tags, including

• change: tags
• added_tags: tags added (CSV or array)
• removed_tags: tags removed (CSV or array)
• author_name
• target_id
• target_type: Project
• target_details: group/project

Alternatively, this could be split into multiple events:

• add: tag
• to: tag_name
• ...

and

• remove: tag . (or is this delete?)
• from: tag_name
• ...

or 'to' and 'from' could both just be 'name'

Links / references

• See the original MR (which was not merged) for guidance on how this should be implemented.