Implement conversion of G4PVReplica to VecGeom PlacedVolumes (#25)

* Import GDML generated from Geant4 Basic Example B5 as of v11.3

Generated by modifying `DetectorConstruction::Construct()` with:

```c++
G4GDMLParser parser;
parser.Write("B5.gdml", worldPhysical);
```

immediately before returning `worldPhysical`.

* Support conversion of G4PVReplica to VecGeom placements

Need identified in AdePT/Celeritas benchmarks using Geant4's example
B5, which uses `G4PVReplica` to model some of its geometry components.
The conversion will fail as `G4PVReplica` has no direct equivalent in
VecGeom.

Implement conversion of `G4PVReplica` by creating individual placements
of the replicated logical volumes. Use `G4ReplicaNavigation` to transform
the volume before creating the placement with this transform. Note that
this only works with rotational or linear replication. Radial replication
implies changes to the underlying solid's dimensions.

Use exported B5 geometry GDML file to implement a unit test of the
conversion. NB: this currently fails due to a seemingly issue with treatment
of pointers in the name of the top volume.

* Remove pointer from main setup volume name

Follows pattern in other test files and needed to get ReplicaTest
unit test to pass.

src/g4vg_impl/Converter.cc

@@ -13,7 +13,9 @@
 #include <G4LogicalVolumeStore.hh>
 #include <G4PVDivision.hh>
 #include <G4PVPlacement.hh>
+#include <G4PVReplica.hh>
 #include <G4ReflectionFactory.hh>
+#include <G4ReplicaNavigation.hh>
 #include <G4VPhysicalVolume.hh>
 #include <VecGeom/management/Logger.h>
 #include <VecGeom/management/ReflFactory.h>
@@ -308,6 +310,18 @@ auto Converter::build_with_daughters(G4LogicalVolume const* mother_g4lv)
                 place_daughter(g4pv);
             }
         }
+        else if (auto* replica = dynamic_cast<G4PVReplica*>(g4pv))
+        {
+            // TODO: check and error if the replica uses the kRaxis replication
+            G4ReplicaNavigation replica_navigator;
+            for (size_type j = 0, jmax = replica->GetMultiplicity(); j != jmax;
+                 ++j)
+            {
+                replica_navigator.ComputeTransformation(j, replica);
+                replica->SetCopyNo(j);
+                place_daughter(replica);
+            }
+        }
         else
         {
             TypeDemangler<G4VPhysicalVolume> demangle_pv_type;

test/G4VG.test.cc

@@ -488,6 +488,93 @@ TEST_F(CmsEeBackDeeTest, no_refl_factory)
     result.expect_eq(this->base_ref());
 }
 
+//---------------------------------------------------------------------------//
+class ReplicaTest : public G4VGTestBase
+{
+  protected:
+    std::string basename() const override { return "B5"; }
+
+    static TestResult base_ref();
+};
+
+TestResult ReplicaTest::base_ref()
+{
+    TestResult ref;
+    ref.lv_name = {
+        "magneticLogical",
+        "hodoscope1Logical",
+        "wirePlane1Logical",
+        "chamber1Logical",
+        "firstArmLogical",
+        "hodoscope2Logical",
+        "wirePlane2Logical",
+        "chamber2Logical",
+        "cellLogical",
+        "EMcalorimeterLogical",
+        "HadCalScintiLogical",
+        "HadCalLayerLogical",
+        "HadCalCellLogical",
+        "HadCalColumnLogical",
+        "HadCalorimeterLogical",
+        "secondArmLogical",
+        "worldLogical",
+    };
+    ref.solid_capacity = {
+        6283185307.179586,
+        400000.0,
+        240000.0,
+        2.4e+07,
+        3.6e+10,
+        400000.0,
+        360000.0,
+        3.6e+07,
+        6.75e+06,
+        5.4e+08,
+        900000.0,
+        4.5e+06,
+        9e+07,
+        1.8e+08,
+        1.8e+09,
+        1.12e+11,
+        2.4e+12,
+    };
+    ref.pv_name = {
+        "magneticPhysical",
+    };
+    // 15 direct placements
+    ref.pv_name.insert(ref.pv_name.end(), 15, "hodoscope1Physical");
+    ref.pv_name.push_back("wirePlane1Physical");
+    // 5 direct placements
+    ref.pv_name.insert(ref.pv_name.end(), 5, "chamber1Physical");
+    ref.pv_name.push_back("firstArmPhysical");
+    // 25 direct placements
+    ref.pv_name.insert(ref.pv_name.end(), 25, "hodoscope2Physical");
+    ref.pv_name.push_back("wirePlane2Physical");
+    // 5 direct placements
+    ref.pv_name.insert(ref.pv_name.end(), 5, "chamber2Physical");
+    // 20x4 = 80 parameterized placements of cellLogical
+    ref.pv_name.insert(ref.pv_name.end(), 80, "cellLogical_param");
+    ref.pv_name.push_back("EMcalorimeterPhysical");
+    ref.pv_name.push_back("HadCalScintiPhysical");
+    // 20 replicas of HadCalLayerLogical
+    ref.pv_name.insert(ref.pv_name.end(), 20, "HadCalLayerLogical_PV");
+    // 2 replicas of HadCalCellLogical
+    ref.pv_name.insert(ref.pv_name.end(), 2, "HadCalCellLogical_PV");
+    // 10 replicas of HadCalColumnLogical
+    ref.pv_name.insert(ref.pv_name.end(), 10, "HadCalColumnLogical_PV");
+    ref.pv_name.push_back("HadCalorimeterPhysical");
+    ref.pv_name.push_back("fSecondArmPhys");
+    ref.pv_name.push_back("worldLogical_PV");
+
+    return ref;
+}
+
+TEST_F(ReplicaTest, default_options)
+{
+    auto result = this->run(Options{});
+    result.expect_eq(this->base_ref());
+}
+
 //---------------------------------------------------------------------------//
 }  // namespace test
 }  // namespace g4vg