Copy SampleCount when making a copy of FilamentView (#7072)

Otherwise the copied view will not be an exact copy - it'll contain the default sample count (=4), and not the sample count of the view it's copying from.

CHANGELOG.md

@@ -1,4 +1,5 @@
 ## Main
+-   Fix MSAA sample count not being copied when FilamentView is copied
 -   Fix TriangleMesh::SamplePointsUniformly and TriangleMesh::SamplePointsPoissonDisk now sampling colors from mesh if available (PR #6842)
 -   Fix TriangleMesh::SamplePointsUniformly not sampling triangle meshes uniformly (PR #6653)
 -   Fix tensor based TSDF integration example.

cpp/open3d/visualization/rendering/filament/FilamentView.cpp

@@ -355,6 +355,7 @@ void FilamentView::CopySettingsFrom(const FilamentView& other) {
     if (other.color_grading_) {
         view_->setColorGrading(other.color_grading_);
     }
+    view_->setSampleCount(other.view_->getSampleCount());
     auto ao_options = other.view_->getAmbientOcclusionOptions();
     view_->setAmbientOcclusionOptions(ao_options);
     auto aa_mode = other.view_->getAntiAliasing();