Calling $detach() discards attributes

[sebffischer]

library(torch)

x = nn_parameter(torch_randn(1))
class(x)
#> [1] "torch_tensor" "R7"           "nn_parameter"
class(x$detach())
#> [1] "torch_tensor" "R7"

^{Created on 2024-02-12 with reprex v2.0.2}

[dfalbel]

We could use a similar approach to what we did for clone, right?

[sebffischer]

Yes, I will PR it. Just noted it down here so it won't be forgotten and I did not want to include even more changes in the cloning PR.