[Runtime] Add Stringification to DLDeviceType and DLDevice

This PR adds `DLDeviceType2String` and overloading of ostream's
`operator<<` on `DLDevice` so that they could be printed as strings more
with better developer ergonomics.

include/tvm/runtime/packed_func.h

@@ -36,6 +36,7 @@
 #include <functional>
 #include <limits>
 #include <memory>
+#include <sstream>
 #include <string>
 #include <tuple>
 #include <type_traits>
@@ -1259,6 +1260,46 @@ inline const char* ArgTypeCode2Str(int type_code) {
   }
 }
 
+/*! \brief Convert a DLDeviceType to string */
+inline std::string DLDeviceType2Str(DLDeviceType ty) {
+  switch (ty) {
+    case DLDeviceType::kDLCPU:
+      return "cpu";
+    case DLDeviceType::kDLCUDA:
+      return "cuda";
+    case DLDeviceType::kDLCUDAHost:
+      return "cuda-host";
+    case DLDeviceType::kDLOpenCL:
+      return "opencl";
+    case DLDeviceType::kDLVulkan:
+      return "vulkan";
+    case DLDeviceType::kDLMetal:
+      return "metal";
+    case DLDeviceType::kDLVPI:
+      return "vpi";
+    case DLDeviceType::kDLROCM:
+      return "rocm";
+    case DLDeviceType::kDLROCMHost:
+      return "rocm-host";
+    case DLDeviceType::kDLCUDAManaged:
+      return "cuda-managed";
+    case DLDeviceType::kDLOneAPI:
+      return "oneapi";
+    case DLDeviceType::kDLWebGPU:
+      return "webgpu";
+    case DLDeviceType::kDLHexagon:
+      return "hexagon";
+    default:
+      return "Device(" + std::to_string(ty) + ")";
+  }
+  throw;
+}
+
+inline std::ostringstream& operator<<(std::ostringstream& os, const DLDevice& device) {
+  os << DLDeviceType2Str(device.device_type) << ":" << device.device_id;
+  return os;
+}
+
 namespace detail {
 
 template <bool stop, std::size_t I, typename F>