[REQUEST] `kDLROCMManaged` type (analogue to  `kDLCUDAManaged`)

Thanks for your good work!

Would it be possible to add a `kDLROCMManaged` to `DLDeviceType`
in `include/dlpack/dlpack.h`?

```c++
 typedef enum {
 //  ...
 kDLROCMManaged = <num>
} DLDeviceType;
```