Add designer specs for BakedLightmap

Designer specs are missing for BakedLightmap, which makes it difficult to use. In long run these would be created/adjusted via baked lighting configuration dialog/view, but in the initial release they will have to be added manually, so the component should be available in components view.

This can be defined on QDS side so we can easily get rid of it in a future version, if necessary, when we provide proper baking configuration support.