Adds a new ResPath struct that will replace ResourcePath (#3663)

Robust.Benchmarks/Utility/ResourcePathBench.cs

@@ -0,0 +1,47 @@
+using BenchmarkDotNet.Attributes;
+using JetBrains.Annotations;
+using Robust.Shared.Analyzers;
+using Robust.Shared.Utility;
+
+#pragma warning disable CS0612
+namespace Robust.Benchmarks.Utility;
+
+[Virtual]
+public class ResourcePathBench
+{
+    private string _path = default!;
+
+    [UsedImplicitly]
+    [Params(10, 100, 1000)]
+    public int N;
+
+    [GlobalSetup]
+    public void GlobalSetup()
+    {
+        _path = "/a/b/c/../test";
+    }
+
+    [Benchmark]
+    public ResPath CreateWithSeparatorResPath()
+    {
+        ResPath res = default;
+        for (var i = 0; i < N; i++)
+        {
+            res = new ResPath(_path);
+        }
+        return res;
+    }
+    
+    [Benchmark]
+    public ResourcePath? CreateResourcePath()
+
+    {
+        ResourcePath? res = null;
+        for (var i = 0; i < N; i++)
+        {
+            res = new ResourcePath(_path);
+        }
+        return res;
+    }
+}
+#pragma warning restore CS0612