Feature: Code Action should use elm proposal for replacement

[andys8]

Elm compiler error messages have proposals how to replace e.g. a typo.

Module build failed: Error: Compiler process exited with error Compilation failed
-- NAMING ERROR - path/Main.elm

Cannot find variable `flag`

53|             flag |> Env.config |> initialModel
                ^^^^
Maybe you want one of the following?

    flags
    flip
    Basics.flip
    Debug.log

Detected errors in 1 module.

This information can be used to give code actions: https://microsoft.github.io/language-server-protocol/specification#textDocument_codeAction

This is currently worked on in: https://github.com/elm-tooling/elm-language-server/tree/code-action