Add basic execution test

Author: aziemchawdhary-gs

legend-pure-core/legend-pure-m3-core/src/main/resources/platform/pure/grammar/milestoning.pure

@@ -270,6 +270,13 @@ function <<test.Test>> meta::pure::test::model::TestBiTemporalClass():Any[*]
   assertEquals(3, $qpFromAssociations->at(5)->genericType().typeArguments->at(0).rawType->toOne()->cast(@FunctionType).parameters->size());
 }
 
+function <<test.Test>> meta::pure::test::model::TestMilestoning():Boolean[1]
+{
+    let instances = ^meta::pure::test::model::ClassWithMilestoning1(businessDate = %2020-01-01);
+    let result1 = meta::pure::test::model::ClassWithMilestoning1.all(%2020-01-01);
+    assertEquals(1, $result1->size());
+}
+