CUDA: C++17 cleanup of ClusterFinderCUDA

- std::array for per-slot state; std::exchange in BatchView::steal
- [[nodiscard]]/noexcept on the public API and release path
- cuda_check moved to aare::cuda::detail (was reserved __cuda_check)
- _v type traits; drop redundant std::move and `using namespace aare`
- Add pytest for BatchView slot release

python/src/bind_ClusterFinderCUDA.hpp

@@ -14,8 +14,6 @@
 namespace py = pybind11;
 using pd_type = double;
 
-using namespace aare;
-
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wunused-parameter"
 
@@ -170,7 +168,7 @@ sqrt(max(sum2/n - mean^2, 0)). Counterpart to `noise` for the device pedestal.)"
         .def(
             "steal_clusters",
             [](CF &self, bool realloc_same_capacity) {
-                return std::move(self.steal_clusters(realloc_same_capacity));
+                return self.steal_clusters(realloc_same_capacity);
             },
             py::arg("realloc_same_capacity") = true)