Tools illink should use runtime formatting

[tlakollo]

ILLink project has a .editorconfig different from runtime global configuration. One of the most important settings is that ILLink uses Mono format inside the .cs files along with a different header file. For now is important to maintain it in case we want to move some commits between dotnet/linker and dotnet/runtime but after the dotnet/linker repo gets archived we want to use the formatting and header from runtime. This issue tracks the work of modifying the .editorconfig once the dotnet/linker repo gets archived