feat(_oak2_mods): add BL4ItemSpawner mod

[Cr4nkSt4r]

No description provided.

[apple1417]

Mostly looks good, the only thing I do need to ask you to change is add requirements via the standard project.dependencies field. But also blimgui isn't in this repo yet - idk what happened with that - and I can't really merge a mod pointing at a dependency that doesn't exist yet, that will really confuse users. I'll just leave the pr open

An extra suggestion I will make though: you're currently overwriting a couple fields when you call build_mod. One of the ideas behind it pulling from the pyproject was you could have a single source of truth - which'd avoid copy paste errors like how your pyproject says unknown coop support, but in game you say client side.