Allow Wiki Renderer links to open in new tab

Wiki Renderer links don't allow the link to be opened in a new tab or window.

With the deprecation of Text Gadget in Jira (Jira Software 9.11.x release notes), more customers are likely to request this feature.

In Jira 9.11, external links may be opened in new tabs by default (if the user has configured such in their profile), but internal links always open within the gadget — not even on the same page in the browser. More on:

• JRASERVER-76350 — Links in Dashboards are no longer opening in new tabs

Example:
Wiki links currently have 3 formats:

[https://site-goes-here.com]

[Custom text goes here|https://site-goes-here.com]

[Custom text goes here|https://site-goes-here.com|Alt Text goes here]

There's no current form to write the wiki link to indicate it should open in a new tab.
Ref.: https://jira.atlassian.com/secure/WikiRendererHelpAction.jspa?section=links