[clang-format] parse C# object initialisers

Summary:
Treat C# object initializers as braced lists.

Allow lambdas inside C# braced lists.

Reviewers: krasimir

Reviewed By: krasimir

Subscribers: cfe-commits, MyDeveloperDay

Tags: #clang-format, #clang

Differential Revision: https://reviews.llvm.org/D75473