Mob collisions (#34580)

* Conveyor optimisations

- Optimise movement for moving stuff. Better flags + less resolves + slapped parallelrobustjob on it.
- Sleeping for entities getting conveyed into walls.

* Blocker version

* Finish

* Final

* Mob collisions

* impulses

* Collision smoothing

* Locked in

* 30tps working

* r

* fixes

* Best

* Fixes + CVars

* CVars in place

* Pushies

* Opt attempt 1

* Revert "Opt attempt 1"

This reverts commit 5ccd72dcbea09261a992aa1f7f05df169a1ce676.

* Fix mispredicts

* Ready-ish

* better

* Cleanup

* Fix conveyor power mispredict

* Forgetting to actually do deltas

* Fix buckle pushes

* Bagel save

* Revert "Bagel save"

This reverts commit 1b93fda81fb852d89b89b0beae0b80f8a61165f2.

* Conveyor resave

* Fix prediction

* Mob movement rewrite

* Bandaid

* Working version

* Tentatively working

* Friction to fix cornering

* More fixes

* Revert bagel

* Revert this

* Bad parity

* Working

* Fixes

* Woops

* Doc comments

* Pen cap cvar

* StandingState cleanup and sub

* Fix downed mobs

* fish

* client

* Disable pushing on tests

* More variables

* Movement mods

* Mass diff

* 1 more tweak

* Cvar

Content.Client/Movement/Systems/MobCollisionSystem.cs

@@ -0,0 +1,42 @@
+using System.Numerics;
+using Content.Shared.CCVar;
+using Content.Shared.Movement.Components;
+using Content.Shared.Movement.Systems;
+using Robust.Client.Player;
+using Robust.Shared.Physics.Components;
+using Robust.Shared.Timing;
+
+namespace Content.Client.Movement.Systems;
+
+public sealed class MobCollisionSystem : SharedMobCollisionSystem
+{
+    [Dependency] private readonly IGameTiming _timing = default!;
+    [Dependency] private readonly IPlayerManager _player = default!;
+
+    public override void Update(float frameTime)
+    {
+        if (!CfgManager.GetCVar(CCVars.MovementMobPushing))
+            return;
+
+        if (_timing.IsFirstTimePredicted)
+        {
+            var player = _player.LocalEntity;
+
+            if (MobQuery.TryComp(player, out var comp) && PhysicsQuery.TryComp(player, out var physics))
+            {
+                HandleCollisions((player.Value, comp, physics), frameTime);
+            }
+        }
+
+        base.Update(frameTime);
+    }
+
+    protected override void RaiseCollisionEvent(EntityUid uid, Vector2 direction, float speedMod)
+    {
+        RaisePredictiveEvent(new MobCollisionMessage()
+        {
+            Direction = direction,
+            SpeedModifier = speedMod,
+        });
+    }
+}