refactor: some types need to setup as `MaybeUninit`

[lonerapier]

Okay, I see. It may be better to swap to MaybeUninit in the future. Can you take note of this?

Originally posted by @Autoparallel in #43

Factor and Key fields defined during setup and derive are later initialized properly during params include, and initially, should be setup as MaybeUininit to prevent any invalid access.

[Autoparallel]

Thanks for making this. Will also be helpful in no-std too.