Create per-project DefaultLightmass.ini

At the moment, There’s only one file (Engine/Config/BaseLightmass.ini) that configures the Lightmass Settings for all projects.
However, it would be great to have these Settings for each project (DefaultLightmass.ini, just like the other Config files).

Plus heckin’ one.

You can make DefaultLightmass.ini file under project Config folder which can override settings that are setuped on DefaultLightmass.ini