[clang-tools-extra] [clangd] Check for editsNearCursor client capability under experimental capabilities (PR #114699)

[Nathan Ridge via cfe-commits]

HighCommander4 wrote:

> > (No action required) – we have other extensions in clangd e.g. `references.container` `offsetEncoding`. Do we plan to do the same thing for them?
> 
> Good question; I was initially thinking of doing it as needed / when someone asks for it. But maybe it would be better to add them all up front, so when a need for another one arises, the support is already in a clangd release. I can do that in a follow-up patch.

Sent out https://github.com/llvm/llvm-project/pull/116531 for this.

https://github.com/llvm/llvm-project/pull/114699