Research entity spawning

[Segfaultd]

Introduction

Actually, the mod offers to spawn peds or cars, either for sync purposes or for NPC.

For a complete MP, we also need to offer to spawn multiple entities: trees, lights, crashobjects, animals etc...

There is also probably a need for proper model allocation reversing.

Scope

This issue only covers the game reversing / playground part and not the network-related part

[Segfaultd]

CrashObj spawning is "working", meaning we can spawn as much as we want, but we have no way to specify which one we want to spawn. It always takes the first available in the resource pack.