[clang-tools-extra] [clangd] Add multiRange support to textDocument/rangeFormatting (PR #80180)

[Tom Praschan via cfe-commits]

tom-anders wrote:

Hmm so it looks like there have been some changes to the proposed LSP spec since my original phabricator diff, so I think I need to adapt this PR a bit. Will convert to a draft for now.

https://github.com/llvm/llvm-project/pull/80180