Move GasMixture to shared (#27480)

* Moved GasMixture to shared

* Temp Fix for sandbox violation, idk why Array.Resize isn't working properly. It's already sandboxed.

* The most powerful webedit in history

Content.Server/Botany/Systems/PlantHolderSystem.cs

@@ -6,6 +6,7 @@ using Content.Server.Fluids.Components;
 using Content.Server.Ghost.Roles.Components;
 using Content.Server.Kitchen.Components;
 using Content.Server.Popups;
+using Content.Shared.Atmos;
 using Content.Shared.Botany;
 using Content.Shared.Burial.Components;
 using Content.Shared.Chemistry.Reagent;