Feature request: support inlay hints and semantic tokens

[WaffleLapkin]

Inlay hints and semantic tokens are both features of LSP that allow getting a lot of information about the code at a glance. It's a big shame live-share does not support them.

I'm mainly using live-share with Rust & rust-analyzer extension for vscode and I'm missing out a lot on those features (there are a lot of useful inlay hints in rust analyzer; semantic tokens are also used by it, for example to highlight unsafe function calls).

[HighCommander4]

A previous issue filed about semantic tokens is #3503, though it seems like it was closed because the issue reporter no longer needed it.

My use case is C++, for which the clangd language server provides much richer semantic highlighting than the client-side TextMate colors, and so my understanding is that LiveShare would need to remote the semantic tokens over from the host (which is where the language server is running) to the guest.