bug#73452: Code lens support in eglot

[Federico Beffa]

Hi,

This is not a bug report, but rather an inquiry or feature request. I'm wondering if there are any plans for eglot to support code lens.

These provide quite useful functionality. For example, the Haskell language server allows putting expressions (typically for test or documentation) in comments with a special syntax. The server then offers to execute the code (in VSCode appearing as a small button above the _expression_). When pressed, it inserts the result in a comment just below. Here's an example after execution:

```haskell
addOne :: (Num a) => a -> a
addOne x = x + 1

-- >>> addOne 2
-- 3
```

Thanks for the great work!
Fede