refactor of model targets and constraints, addition of new constraint types and constraint construction process

app/models/constraints/bundle_constraint.py

@@ -0,0 +1,15 @@
+from random import randint
+
+from models.constraints.generic_constraint import *
+
+class BundleConstraint(GenericConstraint):
+    def build(self, problem_handler: Problem, **kwargs) -> None:
+        logging.info('Bundles Constraint Generating...')
+
+        # TODO: account for many different bundle types, since the id condition in L33 could yield duplicates
+        if problem_handler.bundles != None and len(problem_handler.bundles) > 0:
+            # make sure the total bundles used in generated form is limited between min-max set
+            problem_handler.problem += lpSum([
+                problem_handler.solver_bundles_var[bundle.id] for bundle in problem_handler.bundles
+            ]) == randint(int(self.minimum),
+                        int(self.maximum)), f'Allowing min - max bundles'