gnu: Move web packages from haskell to haskell-web.

gnu: Move web packages from haskell to haskell-web.

* gnu/packages/haskell.scm (ghc-tagsoup, ghc-cookie, ghc-http-types, ghc-http,
ghc-http-client, ghc-http-client-tls, ghc-http-date, ghc-http2,
ghc-http-conduit, ghc-wai, ghc-wai-logger, ghc-wai-extra, ghc-wai-conduit,
ghc-warp, ghc-warp-tls, ghc-xss-sanitize, ghc-css-text, ghc-mime-types,
ghc-html, ghc-xhtml, ghc-blaze-html, ghc-aeson, ghc-aeson-pretty,
ghc-aeson-qq, ghc-multipart): Move variables to ...
* gnu/packages/haskell-web.scm: ... this new file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add it.
* gnu/packages/haskell.scm,
gnu/packages/idris.scm,
gnu/packages/version-control.scm,
gnu/packages/wm.scm: Include haskell-web module.