[clang] [clang-format] Option to ignore macro definitions (PR #70338)

[via cfe-commits]

tomekpaszek wrote:

> After giving more thoughts to this, I think what we really want is `SkipMacroDefinitionBody`, which would format the code below:
> (...)
> That is, only the body (except comments) of a macro definition is not formatted.

I understand that: 
- we do want to align the macros (respect IndentPPDirectives)
- we do want to remove extra whitespaces before, within and right after the first token (#define)
- we do NOT want to touch the body
- we do NOT want to break lines

https://github.com/llvm/llvm-project/pull/70338