* give windowview the ability to show windows from current desktop, all
desktops or current class
* invokable from shortcuts screen edges or gestures
* add a search field to quickly filter
* current present windows effect still present but only internal as is used by desktop grid, which should eventually be ported as well

This can be done either from windowview or overview, tough note that some of the duplication from overview added in windowview is necessary regardless, as WindowHeap, the shared qml part needs some properties exposed from the c++ part.
Implementation wise I'm ok for it being in either place, but i think the functionality of present windows needs to be preserved, otherwise would be a completely unacceptable regression, namely:

* Behavior of what now are the ctrl+f7,f10 and f11 global shortcuts, showing windows of current app (invokable by shoortcut instead of having to use the pointer), windows of current desktop (the only thing overview does atm) or all desktops
* filter on typing, as opposed to invoking krunner. main use case of present windows is quickly switching, and filtering is the most helpful feature, some people do like krunner instead, but is completely out of place for my use case, and i suspect for many other users as well
* also clicking on a taskbar group should be possible to filter
* the view that opens by clicking on a taskbar group should follow the same layout strategy used elsewhere and currently being an effect used only there and not accessible form the list can't even be configured