Extend DynamicHooks to support virtual functions

[KillStr3aK]

With these changes, we will be able to hook virtual functions based on offset.

Example

Testing StartTouch, Touch, EndTouch hooks on the soccerball in de_dust2

{
    "StartTouch": {
        "offsets": {
            "windows": "143",
            "linux": "142"
        }
    },
    "Touch": {
        "offsets": {
            "windows": "144",
            "linux": "143"
        }
    },
    "EndTouch": {
        "offsets": {
            "windows": "145",
            "linux": "144"
        }
    }
}

public CPhysicsPropMultiplayer? SoccerBall;

public VirtualFunctionVoid<CBaseEntity, CBaseEntity>? OnStartTouch;
public VirtualFunctionVoid<CBaseEntity, CBaseEntity>? OnTouch;
public VirtualFunctionVoid<CBaseEntity, CBaseEntity>? OnEndTouch;

public override void Load(bool hotReload)
{
    RegisterEventHandler<EventRoundStart>((@event, info) =>
    {
        IEnumerable<CPhysicsPropMultiplayer> list = Utilities.FindAllEntitiesByDesignerName<CPhysicsPropMultiplayer>("prop_physics_multiplayer");

        if (!list.Any())
        {
            return HookResult.Continue;
        }

        SoccerBall = list.First();

        if (OnStartTouch == null) (OnStartTouch = new VirtualFunctionVoid<CBaseEntity, CBaseEntity>(SoccerBall, GameData.GetOffset("StartTouch"))).Hook(HookOnStartTouch, HookMode.Pre);
        if (OnTouch == null) (OnTouch = new VirtualFunctionVoid<CBaseEntity, CBaseEntity>(SoccerBall, GameData.GetOffset("Touch"))).Hook(HookOnTouch, HookMode.Pre);
        if (OnEndTouch == null) (OnEndTouch = new VirtualFunctionVoid<CBaseEntity, CBaseEntity>(SoccerBall, GameData.GetOffset("EndTouch"))).Hook(HookOnEndTouch, HookMode.Pre);

        return HookResult.Continue;
    });
}

public override void Unload(bool hotReload)
{
    OnStartTouch?.Unhook(HookOnStartTouch, HookMode.Pre);
    OnTouch?.Unhook(HookOnTouch, HookMode.Pre);
    OnEndTouch?.Unhook(HookOnEndTouch, HookMode.Pre);
}

private HookResult HookOnStartTouch(DynamicHook h)
{
    CBaseEntity entity = h.GetParam<CBaseEntity>(0);
    CBaseEntity otherEntity = h.GetParam<CBaseEntity>(1);

    if (entity != SoccerBall && otherEntity != SoccerBall)
        return HookResult.Continue;

    Console.WriteLine($"[OnStartTouch] {otherEntity.DesignerName} ({otherEntity.Index}) started touching {entity.DesignerName} ({entity.Index})");
    return HookResult.Continue;
}

private HookResult HookOnTouch(DynamicHook h)
{
    CBaseEntity entity = h.GetParam<CBaseEntity>(0);
    CBaseEntity otherEntity = h.GetParam<CBaseEntity>(1);

    if (entity != SoccerBall && otherEntity != SoccerBall)
        return HookResult.Continue;

    Console.WriteLine($"[OnTouch] {otherEntity.DesignerName} ({otherEntity.Index}) is touching {entity.DesignerName} ({entity.Index})");
    return HookResult.Continue;
}

private HookResult HookOnEndTouch(DynamicHook h)
{
    CBaseEntity entity = h.GetParam<CBaseEntity>(0);
    CBaseEntity otherEntity = h.GetParam<CBaseEntity>(1);

    if (entity != SoccerBall && otherEntity != SoccerBall)
        return HookResult.Continue;

    Console.WriteLine($"[OnEndTouch] {otherEntity.DesignerName} ({otherEntity.Index}) is no longer touching {entity.DesignerName} ({entity.Index})");
    return HookResult.Continue;
}

Developers should be aware that they are hooking the virtual function, which is shared between instances (same as with signatures)

[KillStr3aK]

This and related constructors are internal because they should not be used randomly. People should only use the exposed VirtualFunctionVoid and VirtualFunctionWithReturn versions

[KillStr3aK]

might need a better way? if we pass another entity instance (ptr) with the same offset it will probably try to hook the same function again and fail? (untested currently, will answer here when I can test it)

[Prefix]

@roflmuffin +1 on this

[KillStr3aK]

@roflmuffin +1 on this

my second review has to be resolved before this pr is ready