9693: feat: Add the Hover Range capability which enables showing the type of an expression r=matklad a=alexfertel Closes https://github.com/rust-analyzer/rust-analyzer/issues/389 This PR extends the `textDocument/hover` method to allow getting the type of an expression. It looks like this:  Edit: One thing I noticed is that when hovering a selection that includes a macro it doesn't work, so maybe this would need a follow-up issue discussing what problem that may have. (PS: What a great project! I am learning a lot! 🚀) Co-authored-by: Alexander Gonzalez <alexfertel97@gmail.com> Co-authored-by: Alexander González <alexfertel97@gmail.com>