qtbase and qtdeclarative feature configuration for footprint-minimized Quick application

Customers want to reduce the QtBase footprint towards the essential requirements of a QML application.

The first version of this was created via QTBUG-117638. Generic Qt build system options and specific Qt feature options where identified as part of this effort. The outcome of this effort is documented by https://doc.qt.io/qt-6/configure-options.html#including-or-excluding-features.

During this investigation is was discovered that some feature options are not properly working. Furthermore there is no existing mapping of features in qtbase and their applicability towards a minimal QML application. The following steps shall be taken to systematically address this problem:

• Create mapping of QML API to qtbase feature required by it
• Document it such that future QML applications can easily match their requirements against the relevant Qt feature configurations
• Identify larger section of the QtBase cde base which are not required at all such for QML use cases and create features to make them optional.
• Fix existing features if they do not work due to build breakages
• Setup an automated system (unit tests? qt configuraitons in the CI...) to ensure new and existing features of QtBase continue to work

Ultimately we want to decrease the ROM footprint of QTBUG-117638 further.