Fixed unnecessary zero-length array allocations

Changed all currently present zero-length array allocations in the codebase to use `Array.Empty` instead.

OpenRA.Mods.Common/UtilityCommands/CreateManPage.cs

@@ -38,7 +38,7 @@ namespace OpenRA.Mods.Common.UtilityCommands
 			Console.WriteLine(".SH OPTIONS");
 
 			var sections = Game.Settings.Sections;
-			sections.Add("Launch", new LaunchArguments(new Arguments(new string[0])));
+			sections.Add("Launch", new LaunchArguments(new Arguments(Array.Empty<string>())));
 			foreach (var section in sections.OrderBy(s => s.Key))
 			{
 				var fields = section.Value.GetType().GetFields();