Add feature for default material when none is selected

I think there should be some option in the settings where you can insert a material that will be displayed on all models that have no model selected. As in when a model is created instead of it being default white it could use a material in the settings kind of like how the skybox works but for models without a material. I would prefer to change the “no material material” to those black and purple squares or perhaps a material that just says missing texture.

Created a ticket for this: Be able to set a material asset to be the default material for primitives on creation · Issue #990 · playcanvas/editor · GitHub