EntityComponentSystem | Summon command

[tillpp]

continuation of #2641
This is just a Draft, don't review yet!
Once i am done, i am going to split this PR into many smaller reviewable PRs

credit for the cubert and moffalo model: @careeoki

TODO List:

• src/server/EntitySystem.zig should use a freed List, to recycle old entity IDs. remove inUse
• make Entities be stored when chunk unloads, if they are NPC (player entities already get stored in the Player file)

requested to be removed by quantum

• Items should use the EntitySystem instead of ItemDrops

moved to issue #2670 in order to be finished before 0.2.0:

• Only give Information about Entities in a range around that player.
• Keep some entity information hidden, depending on who and where the audience is.
• Only send Entitites that moved.

finished:

• Split Components from system
• Let servers/world define themself what entityModel players are allowed, pick one at random when joining
• Custom protocol for component addition/remove and edit
• component Data in storing and transmit should be BInary
• Bug: components aren't stored in Player files, if you exit the world.

This PR adds a /summon <entityType> ?<name> command that let's you spawn an Entity

[IntegratedQuantum]

Items should use the EntitySystem instead of ItemDrops

No, items should remain in a separate system. This is more performant, as they only have the data they really need.