[clang-tools-extra] [clangd] Add option: --limit-hover-contents (PR #155105)

[Nathan Ridge via cfe-commits]

HighCommander4 wrote:

Some high-level feedback:

 1. Hovers contain a variety of types of content (types, values, definitions, initializers, documentation, etc.). This limit applies specifically to macro expansions; therefore, it should have a more specific name, e.g. "limit hover macro expansion" or similar.
 2. Kadir mentioned making this a config option in [this comment](https://github.com/llvm/llvm-project/issues/153355#issuecomment-3187831592), but the current patch is making it a command-line option, is that intentional?

https://github.com/llvm/llvm-project/pull/155105