Enforce indentation style with Clang format

https://clang.llvm.org/docs/ClangFormatStyleOptions.html

Read the linked ClangFormatStyleOptions documentation first, then identify the Objective-C source files and existing project formatting configuration that would be affected. Define the indentation style and the scope of files to format; done means the chosen configuration is applied consistently and the project’s formatting checks or build remain successful.

Written by the indexing model from the issue text.