[clang-tools-extra] [clangd] Store full decl/def range with symbol locations (PR #118102)

[Christian Kandeler via cfe-commits]

ckandeler wrote:

My main motivation is to get DefineOutline out of the proof-of-concept stage where it just dumps the definition somewhere in the same namespace. 
Usually, the location that best fits the user's expectation is next to the definition of an adjacent declaration. If that adjacent declaration follows the one to be moved, then we want to insert the new definition in front of the existing one, which requires us to know where it starts. I don't see how bracket matching can help us get from the name of the function to the actual start of the declaration.

https://github.com/llvm/llvm-project/pull/118102