Take the Transform modules from notebook-language-server-core

[thomasjm]

783 lines deleted here. Ten modules move to core, now that DocumentState is parameterized and none of them name RustNotebookTransformer:

Language.LSP.NotebookLanguageServer.Transform.Util
                                             .Common
                                             .ClientReq
                                             .ClientRsp
                                             .ClientNot.DidSave
                                             .ServerNot
                                             .ServerReq
                                             .ServerRsp
                                             .ServerRsp.Hover
                                             .ServerRsp.Formatting

This repo keeps four modules: its two transformers, their index, and Transform/ClientNot.hs, which is where didOpen builds the transformer and appends .rs. A parameterized version of that is the next change.

ServerRsp.Formatting going to core is worth noting — it is the unproject-based untransform that lets a formatter's output map back into a cell. cpp, go and haskell get it as soon as they implement unproject, which is what currently blocks notebook formatting for them.

-Wunused-packages caught five dependencies that went with the code: lens-regex-pcre, network-uri, pcre-light, random, safe.

19 tests pass.