Split GHC.Driver.Types

I was working on making DynFlags stateless (#17957), especially by
storing loaded plugins into HscEnv instead of DynFlags. It turned out to
be complicated because HscEnv is in GHC.Driver.Types but LoadedPlugin
isn't: it is in GHC.Driver.Plugins which depends on GHC.Driver.Types. I
didn't feel like introducing yet another hs-boot file to break the loop.

Additionally I remember that while we introduced the module hierarchy
(#13009) we talked about splitting GHC.Driver.Types because it contained
various unrelated types and functions, but we never executed. I didn't
feel like making GHC.Driver.Types bigger with more unrelated Plugins
related types, so finally I bit the bullet and split GHC.Driver.Types.

As a consequence this patch moves a lot of things. I've tried to put
them into appropriate modules but nothing is set in stone.

Several other things moved to avoid loops.

* Removed Binary instances from GHC.Utils.Binary for random compiler
  things
* Moved Typeable Binary instances into GHC.Utils.Binary.Typeable: they
  import a lot of things that users of GHC.Utils.Binary don't want to
  depend on.
* put everything related to Units/Modules under GHC.Unit:
  GHC.Unit.Finder, GHC.Unit.Module.{ModGuts,ModIface,Deps,etc.}
* Created several modules under GHC.Types: GHC.Types.Fixity, SourceText,
  etc.
* Split GHC.Utils.Error (into GHC.Types.Error)
* Finally removed GHC.Driver.Types

Note that this patch doesn't put loaded plugins into HscEnv. It's left
for another patch.

Bump haddock submodule