Commented Issue: Source Code Transformations must supports BOM [3174]

Currently , .pp files lost BOM when installed in a Visual Studio project.
Usually, the files operated in Visual Studio are utf-8 with BOM.
Comments: CJK is Chinese/Japanese/Korean characters. Please see attached file 'BOMTestLib.1.0.0.nupkg'. Every .pp files in the nupkg, end with BOM(Byte Order Mark). But, all imported files from that nupkg, lost BOM. I think all utf-8 files must contain BOM in Visual Studio. because every files made by Visual Studio are end with BOM. (And ,Visual Studio failes without BOM , for example aspx files contain Japanese characters.)