Refactor DeviceUVector. (#10595)

Create a wrapper instead of using inheritance to avoid inconsistent interface of the class.

tests/cpp/common/test_device_vector.cu

@@ -12,7 +12,7 @@ TEST(DeviceUVector, Basic) {
   std::int32_t verbosity{3};
   std::swap(verbosity, xgboost::GlobalConfigThreadLocalStore::Get()->verbosity);
   DeviceUVector<float> uvec;
-  uvec.Resize(12);
+  uvec.resize(12);
   auto peak = GlobalMemoryLogger().PeakMemory();
   auto n_bytes = sizeof(decltype(uvec)::value_type) * uvec.size();
   ASSERT_EQ(peak, n_bytes);