Cargo bays should have a local inventory too

[Barthoze]

The current purpose of the Cargo bay is to extend the hull and content of a ship.
As per https://factorio.com/blog/post/fff-382 they do neither accept nor provide any content to avoid ship wide resource teleport

My proposition is as follow : beside providing more space for the central hub, each cargo bay should behave like a separate chest, with possible pluggin to logic networks, and its limited content available for local insertion and retrieval. As for quantities, a quarter of the slots being created for this local use would be useful enough without being game breaking.