Signal the client a refactoring failed

[fm-117]

In my understanding of the refactorings in LSP, there is no dedicated property/notification for the server to signal the client that the refactoring failed. The server can reject a workspace/executeCommand request for example when the parameters are invalid but after that, the server must compute the edits and is expected to send a workspace/applyEdit request. However the ApplyWorkspaceEditParams type does not contain anything to report a problem that occured during the edits computation.

I'd like to have a int? code and string? message properties like in ResponseError directly on ApplyWorkspaceEditParams to describe failed or incomplete refactorings.

Note that the showMessage notification is not appropriate because the client has no info to correlate an incoming showMessage with a previously launched refactoring.