[clang-tools-extra] [clangd] Allow specifying what headers are always included via "" or <> (PR #67749)

[Chiller Dragon via cfe-commits]

ChillerDragon wrote:

Did this already land in 19.1.7? I am having trouble getting it to work.

My ``~/.clangd`` looks like this just to be sure I also put it in ``~/Desktop/git/ddnet/.clangd`` the repo root.

```yaml
CompileFlags:
  Add: -I.
Diagnostics:
  MissingIncludes: Strict
Style:
  AngledHeaders: ["base/.*", "engine/.*", "game/.*"]
```

:LspInfo in neovim confirms I am running clang 19.1.7

```
LSP configs active in this buffer (bufnr: 2) ~
- Language client log: ~/.local/state/nvim/lsp.log
- Detected filetype: `cpp`
- 1 client(s) attached to this buffer
- Client: `clangd` (id: 2, bufnr: [2])
  root directory:    ~/Desktop/git/ddnet/
  filetypes:         c, cpp, objc, objcpp, cuda, proto
  cmd:               ~/.local/share/nvim/mason/bin/clangd
  version:           `clangd version 19.1.7`
  executable:        true
  autostart:         true
```

When I start to call functions from system.h it automatically included it in quotes ._.
I was expecting all base/.* to be angled.

```C++
#include "base/system.h"
```


https://github.com/llvm/llvm-project/pull/67749