adding applySolutionWellState to apply solution from reservoir

to update well state.

With this way, the BlackoilModelEbos does not need to know the data type
assocated with different well type.

It is not well tested yet.

opm/autodiff/WellInterface.hpp

@@ -192,6 +192,11 @@ namespace Opm
         // r = r - C D^-1 Rw
         virtual void apply(BVector& r) const = 0;
 
+        // using the solution x to recover the solution xw for wells and applying
+        // xw to update Well State
+        virtual void applySolutionWellState(const BVector& x, const ModelParameters& param,
+                                            WellState& well_state) const = 0;
+
     protected:
         // TODO: some variables shared by all the wells should be made static
         // well name