Move Items from Starting Inventory to In-Game Shop

[jdrueckert]

In his GSoC 2021 project, @ahv15 extracted the in-game shop from GooeyDefence into Economy from where it's consumed by GooeyDefence and LightAndShadow.

Due to lack of time, actually adding items to the shop was not finished. Terasology/LightAndShadowResources#72 introduces how items can be added to the shop. In addition to adding them to the shop, they will need to be removed from the player's starting inventory where applicable.