Show GPU name when RenderingDevice is unsupported in the project creation dialog

This helps diagnose issues on multi-GPU setups, particularly when
only one of them supports RenderingDevice-based rendering methods.

This can be the case on old laptops with an Intell Haswell IGP
and a NVIDIA Maxwell dedicated GPU, where the IGP does not support
RenderingDevice but the dedicated GPU does.
(In this case, Godot must be forced to run on the dedicated GPU
to allow using RenderingDevice-based rendering methods.)

editor/project_manager/project_dialog.cpp

@@ -986,7 +986,7 @@ ProjectDialog::ProjectDialog() {
 	rvb->add_child(renderer_info);
 
 	rd_not_supported = memnew(Label);
-	rd_not_supported->set_text(TTR("Rendering Device backend not available. Please use the Compatibility renderer."));
+	rd_not_supported->set_text(vformat(TTR("RenderingDevice-based methods not available on this GPU:\n%s\nPlease use the Compatibility renderer."), RenderingServer::get_singleton()->get_video_adapter_name()));
 	rd_not_supported->set_horizontal_alignment(HORIZONTAL_ALIGNMENT_CENTER);
 	rd_not_supported->set_custom_minimum_size(Size2(200, 0) * EDSCALE);
 	rd_not_supported->set_autowrap_mode(TextServer::AUTOWRAP_WORD_SMART);