Add a button to toggle all lights baking in a view on/off

If light are baked, it's difficult to evaluate effect of moving items has on lighting as you need to rebake to see the effect. It would be useful to have a toggle to turn all configured baking off/on for a view.

This could be achieved by setting all BakedLightmap.enabled properties to false and all Light.bakeMode properties to Light.BakeModeDisabled. The original values should be stored to aux properties so they can be reset when baking is toggled back on. Applying baking setup should also toggle baking back on if it's off. If manual mode is specified for baking setup, toggle should be disabled, as tracking changes gets complicated, especially if states are involved.