[Bug] speed regression when using ListConfig in place of tuple when configuring Adam with instantiate

[omry]

#1011 reports performance regression in Adam when using instantiate.
The root cause appears to be that ListConfig is used to configure the betas where tuple or list would be more performant.

Adam is accessing the betas twice per layer during the optimization, which - in some scenarios - is enough to cause a speed regression.

[omry]

To address this, a new instantiation parameter is added:

_convert_ : [none, partial, all]

The parameter can be a par t of the provided conifig or can be specified in the callsite to instanitate.

• _convert_: none : Keep current behavior, passed parameters are DictConfig and ListConfig objects. This is the default behavior for when _convert_ is not specified.
• _convert_ : partial : convert to primitive containers, with the exception of Structured Configs and their nested objects
• _convert_ : all : complete conversion to primitive containers.