Add a quick action to quick-create project level labels

In certain cases it is very cumbersome to go trough the labels view to create a new project level label, therefore it would be nice if there was a quick action for this like /label_new ~<labelname>.

Intended users

Further details

We often use a generic "Support" label to identify issues/tickets that are depending on some third party support (Service providers, external devops etc.), furthermore we also add a label with the ticket/case number of the external ticketing system e.g. a label like "#001200042", those need to be created in the "Labels" view of the project each time, which could be made easier by having a quick action to create a project level label.

Proposal

Add a /label_new ~<labelname> quick action to create a new project level label.

Documentation blurb /label_new ~<labelname> to a new label called "".

Permissions and Security

No new permissions required.

Testing

I can see no risks adding this feature.

What does success look like, and how can we measure that?

Typing /label_new ~#120013001 in the comment box of an issue will create a new project level label with the name "#120013001" and automatically assign it to the current issue.

Feature checklist

Make sure these are completed before closing the issue, with a link to the relevant commit.

Feature assurance
Documentation
Added to features.yml