[Feature Request] add utils.auto_optim

[aron-bordin]

add a simple function on utils, which receives the optimizer name, the model parameters, and its arguments.
This function will create the optimizer and return it.

(if testing multiples optimizers, it's not required to change the code to change an optimizer. you can, for example, use an argument named "optim" and just pass this argument to the function)

[Josecespedesant]

Hey! I'm interested in working on this issue, I see this is kinda old so I'd like to know the state of the initiative 😄