Rust analyzer integration

Hi! I made a mdbook plugin for rust analyzer, which adds inlay hints and hover to code snippets. You can see the book rendered with this plugin.

In my opinion, these features helps reader to have a better sense of what is going on and can solve confusions in some cases.

Current version is at the proof of concept level, but if you are interested, I can fix its problems and make it ready.

If you decide to add this to the book, to avoid confusion, I suggest disabling inlay hints for beginning parts and at some point, adding a paragraph like this:

There is a devtool for rust called rust analyzer, which, among other features, provide hover information and inlay hints in your development environment...... These features help better understanding codes so they are enabled in the book and you will see them in next codes....... Types are hard to write, but good to read, so type inference + inlay hints is win-win.

cc @matklad and rust analyzer guys.

Start by reviewing the linked rendered book and the proof-of-concept plugin described in the issue. Clarify whether the book should adopt the integration and which sections should enable inlay hints; done would require an agreed production-ready plugin and documented integration scope.