[clang-format] Improve handling of C# attributes

Summary:
C# attributes can appear on classes and methods, in which case they should go on their own line, or on method parameters in which case
they should be left inline.

Reviewers: krasimir, MyDeveloperDay

Reviewed By: MyDeveloperDay

Subscribers: klimek

Tags: #clang-format

Differential Revision: https://reviews.llvm.org/D74265