CMake exporter does not handle meshes

When trying to export 3D enabled project from QDS to Creator, some 3D meshes are not present.

Reason for this is this:

• QML tries to load assets from:
  • source: "../asset_imports/Quick3DAssets/PlanetRings/meshes/planet_Ring1_mesh.mesh"
• CMAKE which includes the meshes gives: 
  • /qt/qml/asset_imports/Quick3DAssets/PlanetRings/meshes/planet_Ring1_mesh.mesh
• But the file actually is in
  • build/Qt_6_8_0_for_macOS-Debug/qml/Quick3DAssets/PlanetRings/meshes/planet_Ring1_mesh.mesh

This is works in the QDS environment as the qmlproject knows where things are found but on the CMAKEs these need to be explicit.

This can be reproduced at least with the new Hyperrreal demo:

Clone: git@git.qt.io:qt-demo-team/hyperreal.git

Steps

1. Open the project
2. Enable CMake creation
3. Triggger file update (edit & save a qml file)
4. Close DS
5. Open Creator
6. Open the project
7. Select Qt 6.8 kit
8. Compile & run

What happens: Project starts and renders differently than with QDS

Reason: Assets and shaders are not all loaded.