New event: Approaching unknown shuttle (#24490)

* setup codebase

* Add first shuttle

* tak

* sync striker

* sync 2

* pipipi

* Preloaded roundstart shuttles!

* Make it abstract "PreloaderGrid" not "PreloaderShuttle"

* to do

* added china cuisin shuttle

* fixes

* add disaster evacpod

* remove enemy

* final shuttles

* weight 5 -> 10

* move data to component

* remove autotrailer touching

* doc, respath

* fix frozen positioning

* fixes + cvar

* finally

* fix evacpod

* remove blacklistrules

* remove `UnknownShuttleSpawnRule`, refactor `LoadMapRule` to support preloaded grids

* use tryload

* cleanup

* fixes

* use preloadedgrid for loneops

* weight unknown shuttles differently (preliminal)

* leftover

* cleanup and raffling

* partial review

* singleton gridpreloader no station coupling

* fix grid atmoses

* `roleLoadout` support for `LoadoutComponent`, fix missing gear

* weighting changes

* init logic fix

---------

Co-authored-by: Kara <lunarautomaton6@gmail.com>

Content.Shared/GridPreloader/Prototypes/PreloadedGridPrototype.cs

@@ -0,0 +1,21 @@
+using Robust.Shared.Prototypes;
+using Robust.Shared.Utility;
+
+namespace Content.Shared.GridPreloader.Prototypes;
+
+/// <summary>
+/// Creating this prototype will automatically load the grid at the specified path at the beginning of the round,
+/// and allow the GridPreloader system to load them in the middle of the round. This is needed for optimization,
+/// because loading grids in the middle of a round causes the server to lag.
+/// </summary>
+[Prototype("preloadedGrid")]
+public sealed partial class PreloadedGridPrototype : IPrototype
+{
+    [IdDataField] public string ID { get; } = string.Empty;
+
+    [DataField(required: true)]
+    public ResPath Path;
+
+    [DataField]
+    public int Copies = 1;
+}