Jira Importer - Status quo discovery

Related to https://gitlab.com/gitlab-com/Product/-/issues/12908 we are looking to enhance our Jira importer by allowing customers to migrate additional items.

First, we need to assess the status quo of our Jira Importer and answer the following questions with regards to

• What are the current capabilities of our Jira Importer and what are the known issues?
• We should review our if our documentation is up-to-date. For example, Issues are already supported, but there is not a mention of comments, attachments, etc
• "The Jira importer is not currently accessible if you were to create a new project and select "Import" although I wonder if that is because I don't have the integration setup".

I will create separate threads for these items below: