CVE-2025-59842: JupyterLab LaTeX typesetter links did not enforce `noopener` attribute

Links generated with LaTeX typesetters in Markdown files and Markdown cells in JupyterLab and Jupyter Notebook did not include the noopener attribute.

This is deemed to have no impact on the default installations. Theoretically users of third-party LaTeX-rendering extensions could find themselves vulnerable to reverse tabnabbing attacks if:

• links generated by those extensions included target=_blank (no such extensions are known at time of writing) and
• they were to click on a link generated in LaTeX (typically visibly different from other links).

For consistency with handling on other links, new versions of JupyterLab will enforce noopener and target=_blank on all links generated by typesetters. The former will harden the resilience of JupyterLab to extensions with lack of secure defaults in link rendering, and the latter will improve user experience by preventing accidental state loss when clicking on links rendered by LaTeX typesetters.