Standalone app to run all samples to catch run time exceptions. (#3309)

* Run all samples.

* changes.

* comment temp stuff out.

* Revert "comment temp stuff out."

This reverts commit ad74e0fb91bad5de4a4e98b98402e9cc83b6acc0.

* comment temp stuff.

* cleanup.

* revert.

* PR feedback.

* PR feedback.

Author: codemzs

docs/samples/Microsoft.ML.Samples/Microsoft.ML.Samples.csproj

@@ -4,6 +4,7 @@
     <TargetFramework>netcoreapp2.1</TargetFramework>
     <OutputType>Exe</OutputType>
     <SignAssembly>false</SignAssembly>
+    <!--This ensures that we can never make the mistake of adding this as a friend assembly. Please don't remove.-->
     <PublicSign>false</PublicSign>
     <RootNamespace>Samples</RootNamespace>
   </PropertyGroup>

docs/samples/Microsoft.ML.Samples/Program.cs

@@ -1,12 +1,27 @@
-using Samples.Dynamic;
+using System;
+using System.Reflection;
 
 namespace Microsoft.ML.Samples
 {
-    internal static class Program
+    public static class Program
     {
-        static void Main(string[] args)
+        public static void Main(string[] args) => RunAll();
+
+        internal static void RunAll()
         {
-            CalculateFeatureContribution.Example();
+            int samples = 0;
+            foreach (var type in Assembly.GetExecutingAssembly().GetTypes())
+            {
+                var sample = type.GetMethod("Example", BindingFlags.Public | BindingFlags.Static | BindingFlags.FlattenHierarchy);
+
+                if(sample != null)
+                {
+                    sample.Invoke(null, null);
+                    samples++;
+                }
+            }
+
+            Console.WriteLine("Number of samples that ran without any exception: " + samples);
         }
     }
 }