Rework Final Tagless engine

[graninas]

Currently, FT is implemented closely in the MeteorCounter app. It should be somehow reworked and turned into a framework to enable its usage without reinventing the stuff.

There are modules FTL and FTLI but these modules are not quite about Final Tagless.

In app/MeteorCounter/FTL.hs:

-- Flaws of FT
-- - BL depends on Runtime
-- - BL and implementation works in the same Runtime
-- - Implementation details leak into BL through type classes
--   (see logger type classes with additional type variables)
-- - Advanced language features (type classes + Type Families)
-- - Single runtime for all language interpreters
-- - Implicit type class instances (not values)
-- -

newtype AppM a = AppM { runAppM :: ReaderT R.CoreRuntime IO a }
  deriving (Functor, Applicative, Monad, L.ControlFlowL, L.LoggerL, L.RandomL, L.ProcessL)

class
  ( L.StateL (L.Transaction m)
  , L.Atomic m
  , L.LoggerL m
  , L.RandomL m
  , L.ControlFlowL m
  , L.ProcessL m
  ) => Lang m
instance Lang AppM

instance L.Atomic AppM where
  type Transaction AppM = STM
  transaction = AppM . atomically