[Feature Request] Consider updating Mermaid.js.

**Describe the solution you'd like**
The latest version of Mermaid introduces a number of new features, one of which is improved namespace integration for class diagrams. Could we get an update to Mermaid 11.15.0 or later?

No file or test is named. Locate the Mermaid.js dependency or integration entry point in Docfx, check the current Mermaid version, and review the Mermaid 11.15.0 release changes relevant to class-diagram namespace integration. Done means the supported Mermaid version is updated and the integration still builds and renders the affected diagrams.

Written by the indexing model from the issue text.