LSP Code Action: Convert inexhaustive let to case

[GearsDatapacks]

For example, you have this code:

pub type Wibble {
  Wibble(wibble: Int)
}

pub fn main(wibble: Wibble) {
  let Wibble(inner) = wibble
  do_something_with(inner)
}

But then you change the Wibble type:

pub type Wibble {
  Wibble(wibble: Int)
  Wobble(wobble: Int)
}

The let expression now fails to compile. It could be useful to have a code action to turn:

let Wibble(inner) = wibble

into:

let inner = case wibble {
  Wibble(inner) -> inner
  _ -> todo
}

This would be very similar to the code action to convert let assert to case, except it would only be offered if the let expression is not exhaustive.

[giacomocavalieri]

I love the idea!

[GearsDatapacks]

I can work on this. It should be pretty trivial to adapt the existing code action to work in this case too