Add referrer property to Jira Links inside GitLab

Problem to solve

We now have a few features that are connecting GitLab directly in to Jira, such as in the navigation sidebar, or viewing the details of an issue from the Issue List. Because this traffic looks like any other, Atlassian has no insight as to how much usage is being driven by the features we're adding. They've requested that we add a referrer string anywhere that we're linking directly to Jira.

Proposal

Append a referrer property to any links in GitLab that are sending the user to Jira Cloud:

• On gitlab.com: atlOrigin=eyJpIjoiY2QyZTJiZDRkNGZhNGZlMWI3NzRkNTBmZmVlNzNiZTkiLCJwIjoianN3LWdpdGxhYi1pbnQifQ
• On self-managed instances: atlOrigin=eyJpIjoiYjM0MTA4MzUyYTYxNDVkY2IwMzVjOGQ3ZWQ3NzMwM2QiLCJwIjoianN3LWdpdGxhYlNNLWludCJ9
• On development and test environments: don't append anything

Documentation for this can be found here: https://developer.atlassian.com/developer-guide/client-identification/

These links can be found in the following locations:

• In the Jira Issues -> Open Jira sidebar link
• On the Jira Issue List, when clicking on an issue
• On the Jira Issue List, when clicking Create new issue in Jira
• Referencing a Jira issue. For your information, there is another issue related to the web URLs that we can take into consideration #329420 (closed)
  • On an MR detail view, in the title and description, when referencing a Jira Issue
  • On a Commit detail view, in the description, when referencing a Jira issue