Jetpacks (#9023)

* Movement acceleration

* tweaks

* Weightless refactor coz fuck it

* CCVars

* weightless movement tweaks

* Some cleanup while I'm here

* dorkpacks

* thanks fork

* fixes

* zoomies

* toggles

* hmm

* yamls

* b

* so true

* Effects refactor

* namespace

* review

Content.Shared/Movement/Events/WeightlessMoveEvent.cs

@@ -0,0 +1,14 @@
+namespace Content.Shared.Movement.Events;
+
+/// <summary>
+/// Raised on an entity to check if it can move while weightless.
+/// </summary>
+[ByRefEvent]
+public struct CanWeightlessMoveEvent
+{
+    public bool CanMove = false;
+
+    public CanWeightlessMoveEvent()
+    {
+    }
+}