Expose P_MakeSoftwareCorona to Lua as P_CreateFakeCorona

I've converted this function to Lua for many different functions at this point. I feel like it should be exposed. It's quite simple of a function and is extremely useful.

The rational for doing this edit instead of just making one entirely in Lua is that the function already exists in the source code for a few objects. so why not just expose that function.

example script: coronatest.lua

demonstration of script: