[Development] Request to rename module qtscxml to qtstatemachine

[Ulf Hermann]

> with Qt6 we removed the QtStateMachine implementation  from qtbase and 
> moved it into qtscxml. While the name was ok when the module contained 
> only SCXML releated code, it contains now both state machine 
> implementations. Hence I would like to propose/request to rename the 
> module to qtstatemachine to reflect the widened code base. Jira task: 
> QTBUG-89837 <https://bugreports.qt.io/browse/QTBUG-89837>

Indeed, that's a much better name. +1