Embedded performance application analysis

There is a mother epic for perfomance metrics for embedded. This ticket tracks initial analysis for that epic to see if we would need a separate embedded performance benchmark app:
-how much do the current 3D and QML benchmarking apps provide
-how much would the cross-area application profiling work item help here
-document technical use cases for embedded apps - what are all the aspects we need take into account
-potential additions into performance tuning guidelines

Current guidelines:
-do not use Qt modules that rely on SW rendering such as QtCharts, the target is to use HW rendering whenever possible

-follow the best practices for Qt Quick, especially including QML cmake API so that qmllint and qmlsc as well as qmltc are available. These are however commercial only.

https://doc-snapshots.qt.io/qt6-dev/qtquick-bestpractices.html

-For drawing custom UI elements, do not use Canvas QML type but images/textures and Shader Effects (https://doc.qt.io/qt-6/qml-qtquick-shadereffect.html). Shaders require HW acceleration (GPU).

-Using Qt Quick it's possible to use either hw accelerated or software rendering backend. Using Qt Widgets on embedded is not recommend as it's always using software rendering.

-choose resolution appropriately for the UI size, need to be careful in particular with higher resolutions such as 720p as higher resolution has performance impacts

-Use Window as application root element and set application backround color for it. Do not use full screen Item as application root item! Doing so has big negative performance impact.