add(Actor): ActorRespawnSystem and ActorRespawnTimer

[targun123]

Hi! I noticed that Pull Requests are disabled, so I'm sharing my implementation of the NPC/Monster respawn system here.

You can review the changes directly on my fork here:
targun123@edbf0e1

Features:

• Added ActorRespawnTimer component to hold template ID, delay, and spawn position.
• Added ActorRespawnSystem to update elapsed time since death and handle respawning via World::addNpc.

[Chnossos]

Hello! I must say, I wasn't expecting something like this to happen ahah.

I have disabled Pull Requests because for now the code base is too unstable and subject to heavy changes on my part and I don't want to mess with code that doesn't come from my own head.

As you saw, the spawn system is not made yet because I am working on a very big part: data persistence into a database. That said, I have plans for a more fleshed out spawn system than this, so stay tuned for future updates! I am actively working on this project.