rework the inventory menu to be more flexible, and add rando features

[duncathan]

• changed the arrays of items defining the tabs to be arrays of structs, with an optional bool argument for whether to render as full-width
• generalized the item columns rendering to handle the new full-width feature, so each tab now just makes a single function call to render
• use an ImGui table to render in columns, rather than groups and SameLine
• slightly reorganizes the General and Weapons tabs
• adds handling for rando's various custom items, behind the RANDOMIZER define
• adjust the All items button to get max capacity dynamically, rather than defining the capacities statically

[duncathan]

here are some screenshots of the new layout, first in no-rando mode:

(ignore varia being a slider, that's a quirk of my testing setup)

and in rando mode:

[henriquegemignani]

I guess this comment already existed, but there's no need for this in Echoes I believe

[duncathan]

yeah I just left it in as I restructured, but could easily remove