Refactor CommandResolver into individual CommandResolver Implementation

classes.

Write Unit Tests covering Composite DefaultCommandResolver and
ScriptCommandResolver.

baseline

Baseline2

src/Microsoft.DotNet.Cli.Utils/CommandResolution/IPackagedCommandSpecFactory.cs

@@ -0,0 +1,21 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using Microsoft.DotNet.ProjectModel.Graph;
+
+namespace Microsoft.DotNet.Cli.Utils
+{
+    public interface IPackagedCommandSpecFactory
+    {
+        CommandSpec CreateCommandSpecFromLibrary(
+            LockFilePackageLibrary library,
+            string commandName,
+            IEnumerable<string> commandArguments,
+            IEnumerable<string> allowedExtensions,
+            string nugetPackagesRoot,
+            CommandResolutionStrategy commandResolutionStrategy,
+            string depsFilePath);
+        
+    }
+}