Improved configurations for X-Ray

[xeolabs]

Two changes to xeokit SDK Viewer configs give us better X-Ray in BIMViewer.

Disable Depth masking:

const viewer = new Viewer({
            localeService: cfg.localeService,
            canvasElement: canvasElement,
            keyboardEventsElement: cfg.keyboardEventsElement,
            transparent: false,
            backgroundColor: [1, 1, 1],
            backgroundColorFromAmbientLight: false,
            saoEnabled: true,
            pbrEnabled: false,
            colorTextureEnabled: true,
            alphaDepthMask: false,  <<--------------------- Disable depth masking
            numCachedSectionPlanes :4
        });

Improved X-Ray material configs:

 _customizeViewer() {
        const scene = this.viewer.scene;
        scene.xrayMaterial.fill = true;
        scene.xrayMaterial.fillAlpha = 0.1;
        scene.xrayMaterial.fillColor = [0.5, 0.5, 0.5];
        scene.xrayMaterial.edges = true;
        scene.xrayMaterial.edgeAlpha = 0.2;
        scene.xrayMaterial.edgeColor = [0.3, 0.3, 0.3];

Much better X-Ray effect as a result: