Untransform workspace/applyEdit so edits reach the client as notebook edits

[thomasjm]

Depends on codedownio/notebook-language-server-core#4.

workspace/applyEdit reached the client naming the shadow document, at the shadow document's coordinates, so the client refused it. Core untransforms it now, which makes transformServerReq monadic — hence the one-line change in app/Main.hs.

This also picks up core#2, which made textDocument/formatting opt-in. StripDirective and HeadTailTransformer both implement unproject, so notebookConfigHandlesFormatting = True keeps formatting working.