Missing qt3d-runtime in boot2qt image

Adding the new description. to reflect the current needs as discussed.

The Neptune3 UI in 5.13 uses a version of Qt 3D Studio runtime in combination with Qt 5.13. This combination is or better was not supported by Qt 3D Studio. Moreover, Qt 3D Studio has changed the default runtime along the releases of Neptune3 UI. Plus, there was the problem QT3DS-3740 with the new runtime. These are the key reasons why we were not able to include the runtime in the images of Qt Auto so far, even though the use of it was documented. We still want to do this to be able show the shiny 3D objects powered by Qt 3D Studio on regular basis. With the release of 2.5 we will have a chance to get in-sync and get this done. Unfortunately, 2.5 will be released after Qt Auto 5.13.1. The plan is then to include the runtime from 2.5 in 5.13.2. Since we do not seem to have other pending changes for 5.13.2, this inclusion and an update to Qt 5.13.2 would be the only changes we need to make.

Old description:
"
qt3d-runtime (branch 2.4) is required for Neptune 3 UI Vehicle app. The last version of Qt3DStudio provides runtime based on opengl, our app depends on old runtime based on qt3d.
If qt3d-runtime (branch 2.4) is built with boot2qt toolchain and installed into the target, everything works as expected.
"