[clang] [llvm] [clang-format] Add cmake target clang-format-style-options for updating ClangFormatStyleOptions.rst (PR #111513)

[Nikita Popov via cfe-commits]

nikic wrote:

Reverted this because it breaks a the build. I initially assumed this is due to disabled docs per the previous comment, but I think in my case the problem is actually that this seems to be trying to write to the source directory, which is forbidden. If you need to write out files, that has to happen in the build directory.
```
FAILED: /var/llvm-compile-time-tracker/llvm-project/clang/docs/ClangFormatStyleOptions.rst 
cd /var/llvm-compile-time-tracker/llvm-project/clang/docs/tools && /usr/bin/python3.10 dump_format_style.py
Traceback (most recent call last):
  File "/var/llvm-compile-time-tracker/llvm-project/clang/docs/tools/dump_format_style.py", line 23, in <module>
    with open(PLURALS_FILE, "a+") as f:
PermissionError: [Errno 13] Permission denied: '/var/llvm-compile-time-tracker/llvm-project/clang/docs/tools/plurals.txt'
```

https://github.com/llvm/llvm-project/pull/111513