[clang] [clang-format] clang-format-ignore: Add support for double asterisk patterns (PR #110560)

[Sergey Dikiy via cfe-commits]

GloryOfNight wrote:

I want to express support for this feature. Just today I attempted to integrate .clang-format-ignore and was really confused by fact that it cannot ignore recursively. Project I wanted to integrate it to has a lot of generated files which is all over the place. It's very inconvenient have to use that pattern for every directory I want to ignore:
```
imported/*
imported/*/*
imported/*/*/*
```
`DisableFormat ` is also inconvenient, since placing .clang-format with disabled formatting all over the project not exactly a solution I would want to go with either.

Just having single .clang-format-ignore file with `imported/**` would be much more convenient way to do things. IMO.


https://github.com/llvm/llvm-project/pull/110560