[Clangd] Make the type hint length limit configurable

This commit is about clangd's type name hint length limit. The past behavior was 32 characters fixed limit. It is now configurable.

Projects can now add the following config fragment to their .clangd:

```
InlayHints:
  TypeNameLimit: 34
```

Ref: [[ https://github.com/clangd/clangd/issues/1357  | Make the type hint length limit configurable ]]

Reviewed By: hokein

Differential Revision: https://reviews.llvm.org/D147395