Per-target subdirectories

[dijkstracula]

A suggestion from Jigar: with P projects where more than one target might be used, it might make sense to extract e.g. all generated C# files into PGenerated/dotnet, all generated Java files into PGenerated/java, and so on. Similarly, foreign function implementations could have a similar structure (i.e. PForeign/dotnet/MyMagicalClass.cs and PForeign/java/MyMagicalClass.java, etc)

[ankushdesai]

I support this change, I agree, it would be helpful.

[dijkstracula]

Unassigning this from me since I won't get to it before my internship ends.

[ankushdesai]

We have not come across a case where a team using multiple backends. Closing this issue for now and will re-open if needed.