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

[Owen Pan via cfe-commits]

owenca wrote:

After giving more thoughts to this, I think what we really want is `SkipMacroDefinitionBody`, which would format the code below:
```
   # define   A   a. b   //comment
   # define   A( x , y )   ( ( x ) + ( y ) )
```
To the following:
```
#define A   a. b // comment
#define A(x, y)   ( ( x ) + ( y ) )
```
That is, only the body (except comments) of a macro definition is not formatted.

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