Player Containers

this version is still for BlanketCon '25, it just has some tweaks:

• contained players (which previously had collisions with all blocks as in any other gamemode) now can pass through blocks that are non-opaque or that have blockentity-based rendering
• item rarities fixed (singularity container -> epic, self container -> rare)
• contained players now properly collide with the container radius (as opposed to before where they were teleported back every tick)
• command outputs tweaked slightly (release now outputs whether the release was successful or not, op-exclusive commands now log their outputs)