Refactor Ammunition

[NanakoAC]

When created, magazines create all the bullets inside them too. This amounts to thousands of bullets spawned at runtime for no reason, it is a terrible design.

To fix this, magazines need to be designed to only spawn bullets when needed. If a mag contains only one type of ammo, the bullets in it can be virtual, just track the quantity and spawn a new round on request

The type of bullet in the mag can be changed if its completely emptied and then loaded with a different type.

We only ever need to simulate the contents if the mag is loaded with a mixture of different rounds

[LudwigVonChesterfield]

Actually, if it's fille with a mixture of different rounds, instead of "simulating contents" what could be done is a list of types of "bullets" to spawn.