Initialise Guide Rate Object From Restart File

This commit adds an overload set named

    loadRestartGuideRates

which, collectively, initialises the contained GuideRate object
using guide rate values from the restart file.  This is necessary,
but not quite sufficient, to restart models in prediction mode with
group-level constraints.

opm/simulators/wells/BlackoilWellModelGeneric.hpp

@@ -307,6 +307,14 @@ protected:
     void loadRestartGroupData(const std::string&     group,
                               const data::GroupData& value);
 
+    void loadRestartGuideRates(const int                    report_step,
+                               const GuideRateModel::Target target,
+                               const data::Wells&           rst_wells);
+
+    void loadRestartGuideRates(const int                                     report_step,
+                               const GuideRateConfig&                        config,
+                               const std::map<std::string, data::GroupData>& rst_groups);
+
     std::unordered_map<std::string, data::GroupGuideRates>
     calculateAllGroupGuiderates(const int reportStepIdx) const;