[T/NL] Use unique_ptr for mesh.

Tests/NumLib/TestMeshComponentMap.cpp

@@ -39,12 +39,11 @@ class NumLibMeshComponentMapTest : public ::testing::Test
     ~NumLibMeshComponentMapTest() override
     {
         delete cmap;
-        delete mesh;
     }
 
     static std::size_t const mesh_size = 9;
-    MeshLib::Mesh const* mesh =
-        MeshLib::MeshGenerator::generateLineMesh(1.0, mesh_size);
+    std::unique_ptr<MeshLib::Mesh> const mesh{
+        MeshLib::MeshGenerator::generateLineMesh(1.0, mesh_size)};
 
     //data component 0 and 1 are assigned to all nodes in the mesh
     static std::size_t const comp0_id = 0;