Move LANGUAGE pragmas from .hs files to .cabal files

[srid]

For eg:

neuron/src/Neuron/Config.hs

Lines 1 to 13 in 6917658

	{-# LANGUAGE DeriveAnyClass #-}
	{-# LANGUAGE DeriveGeneric #-}
	{-# LANGUAGE DerivingStrategies #-}
	{-# LANGUAGE FlexibleContexts #-}
	{-# LANGUAGE LambdaCase #-}
	{-# LANGUAGE OverloadedStrings #-}
	{-# LANGUAGE QuasiQuotes #-}
	{-# LANGUAGE RecordWildCards #-}
	{-# LANGUAGE ScopedTypeVariables #-}
	{-# LANGUAGE StandaloneDeriving #-}
	{-# LANGUAGE TypeApplications #-}
	{-# LANGUAGE ViewPatterns #-}
	{-# LANGUAGE NoImplicitPrelude #-}

The bulk of these can be moved to neuron.cabal under default-extensions.

Make sure that this doesn't break bin/* scripts or HLS.

cf. https://kowainik.github.io/posts/extensions#cabal-default-extensions-per-stanza