1bpp PNG image can't be loaded as Quick3D 5.x Texture

This should've been fixed in Qt 6.x.

Since QSSGLoadedTexture::loadQImage() doesn't covert QImage::Format_Mono to 8bit/32bit color space, loading 1bpp PNG would crash or upload garbage data.

https://code.qt.io/cgit/qt/qtquick3d.git/tree/src/runtimerender/resourcemanager/qssgrenderloadedtexture.cpp?h=5.15.2#n57

As a workaround, we can make QQuickImage process 1bpp png:

                diffuseMap: Texture {
                    sourceItem: Image { source: "assets/quick-fox-1bpp.png" }
                }

but unfortunately, this doesn't work for TextureInput of CustomMaterial as of Qt 5:

        property TextureInput myTexture: TextureInput {
            texture: Texture {
                sourceItem: Image { source: "assets/quick-fox-1bpp.png" }
            }
        }

Project to reproduce the problem is attached.