Rider static analysis (#433)

* Non-accessed local variable

* Merge cast and type checks.

* StringComparison.Ordinal added for better culture support

* Supposed code improvement in launcher. Remove unused code.

* Update ExplosionHelper.cs

Unintentional change.

* Optimized Import

* Add Robust.Shared.Utility import where it was deleted

* Other random suggestion

* Improve my comment

Content.Client/Construction/ConstructionPlacementHijack.cs

@@ -1,14 +1,11 @@
 using Content.Client.GameObjects.Components.Construction;
 using Content.Shared.Construction;
-using Robust.Client.Graphics;
 using Robust.Client.Interfaces.ResourceManagement;
 using Robust.Client.Placement;
-using Robust.Client.ResourceManagement;
 using Robust.Client.Utility;
 using Robust.Shared.Interfaces.GameObjects;
 using Robust.Shared.IoC;
 using Robust.Shared.Map;
-using Robust.Shared.Maths;
 
 namespace Content.Client.Construction
 {
@@ -46,7 +43,6 @@ namespace Content.Client.Construction
         {
             base.StartHijack(manager);
 
-            var res = IoCManager.Resolve<IResourceCache>();
             manager.CurrentBaseSprite = Prototype.Icon.DirFrame0();
         }
     }