Port Qt Location to Qt 6

Qt Location has been part of Qt 5 and not been part of the essential and most-used module list for migration to Qt 6.
Over time, we received a multitude of customers and OSS projects demanding reviving Qt Location.
After several discussions with customers the scope could be narrowed down. For more details, follow this spreadsheet:
Qt6Location_CustomerFeedback.xlsx

The most relevant items are:
-         Capability to render map tiles onto a QML scene
-         Gesture operation (pinch/zoom/move/…)
-         Render custom items on top of the map. Open: Do we need QMapItem, or can it be integrated into the “regular” scene
Open Question: Preferably the rendering should happen on top of RHI instead of a hard dependency to OpenGL. This allows future proof implementation of mapping support. Effort is yet to be estimated.
Features which are not or only by a few required:
-         Points of Interest API
-         Navigation

Backends to be supported:
-         OSM

A couple of customers have been integrating other map providers, so we should make sure that the backend API is flexible enough. However, the Qt 5 version already was sufficient to them. Some map providers do not allow abstraction of their services, hence we as the Qt Company cannot provide a backend, customers can do it for their specific projects though.

R&D activities can be followed here: https://bugreports.qt.io/browse/QTBUG-72239