Enhancement: Move upgrade items to Core and unify the upgrades between the two mods

[Twisted-Code]

I distinctly remember one time on my 1.18 server a few months ago where I had to refund someone because they accidentally made the Sophisticated Storage void upgrade instead of the Sophisticated Backpacks version. Is there any way you can unify the items themselves, even if you have to have them activate different code under the hood? I presume that's one of the reasons they are still separate, right? The backpack versions have additional code to handle player tick events etc.
But really, couldn't the code for the Backpack upgrades work for Storage and just disable the irrelevant code?

[Twisted-Code]

possible alternative (which I may implement on my end in the meantime, and maybe PR if I can get GIT hooked up to github again): add crafting recipes to convert one version to the other and vice versa. At least then making the wrong "void upgrade" is not as bad