QDoc: Include obsolete QML members in templates

QDoc's Template Generator omits deprecated QML member details. Thus,
readers can't see deprecation notes, and member lists link to missing
anchors. Inherited members can also link to an `\internal` base type
that has no published page.

This change teaches the Template Generator how to provide
obsolete-member pages. Links to inherited members lead to the concrete
type's documentation. This completes deprecation-note coverage alongside
the aggregate and scheduled notes.

Fixes: QTBUG-151328
Pick-to: 6.12
Change-Id: I445f362d667f8c5695096b7f76de8639e600701b
Reviewed-by: Topi Reinio <topi.reinio@qt.io>