qdoc: Add status description to the requisites table

QDoc supports multiple ways to document the status of a C++ class or a QML type: Deprecated, deprecated since <version>, preliminary, or a custom status, typically 'Technology preview'.

This status information is reflected on different parts of the documentation; An auto-generated sentence in the detailed description of the type and/or it's module page, or in the navigation (breadcrumbs) for HTML output.

Add the status to the 'requisites' table on of of the type reference - it's a logical place for this information and makes it easier to discover.