Refactor and update sample project build. (dotnet#3816)

* Refactor and update sample project build.

Scope: Make samples build with nor or minimal changes to actual snippets usied in docs.

Added namespaces to organize code and prevent naming conflicts. Used filename as namespace, and for files with names of classes, added "CS" to namespace

Adjusted `using` directives to include necessary references to make build pass.

Wrapped code snippets in conditional compilation directives for mostly  .NET Framework-specific APIs.

Made some changes to the .csproj file to enable local "dotnet build" - happy to revert as needed.

* Fix indent

* Update comment style

Author: ErikEJ

doc/samples/ApplicationClientIdAzureAuthenticationProvider.cs

@@ -2,7 +2,7 @@
 using System;
 using Microsoft.Data.SqlClient;
 
-namespace CustomAppIdAuthProviderExample
+namespace ApplicationClientIdAzureAuthenticationProvider
 {
     public class Program
     {

doc/samples/AzureKeyVaultProviderExample_2_0.cs

@@ -6,7 +6,7 @@
 using Microsoft.Data.SqlClient;
 using Microsoft.Data.SqlClient.AlwaysEncrypted.AzureKeyVaultProvider;
 
-namespace Microsoft.Data.SqlClient.Samples
+namespace AzureKeyVaultProviderExample_2_0
 {
     public class AzureKeyVaultProviderExample_2_0
     {

doc/samples/AzureKeyVaultProviderWithEnclaveProviderExample.cs

@@ -1,4 +1,5 @@
-using System;
+#if false
+using System;
 //<Snippet1>
 using System.Collections.Generic;
 using System.Security.Cryptography;
@@ -7,7 +8,7 @@
 using Microsoft.Data.SqlClient.AlwaysEncrypted.AzureKeyVaultProvider;
 using Microsoft.IdentityModel.Clients.ActiveDirectory;
 
-namespace AKVEnclaveExample
+namespace AzureKeyVaultProviderWithEnclaveProviderExample
 {
     class Program
     {
@@ -264,3 +265,4 @@ public CustomerRecord(int id, string fName, string lName)
     }
 }
 //</Snippet1>
+#endif

doc/samples/AzureKeyVaultProviderWithEnclaveProviderExample_2_0.cs

@@ -6,7 +6,7 @@
 using Microsoft.Data.SqlClient;
 using Microsoft.Data.SqlClient.AlwaysEncrypted.AzureKeyVaultProvider;
 
-namespace AKVEnclaveExample_2_0
+namespace AzureKeyVaultProviderWithEnclaveProviderExample_2_0
 {
     class Program
     {

doc/samples/AzureKeyVaultProvider_ColumnEncryptionKeyCacheScope.cs

@@ -3,7 +3,7 @@
 using Microsoft.Data.SqlClient;
 using Microsoft.Data.SqlClient.AlwaysEncrypted.AzureKeyVaultProvider;
 
-namespace AzureKeyVaultProviderExample
+namespace AzureKeyVaultProvider_ColumnEncryptionKeyCacheScope
 {
     // <Snippet1>
     class Program

doc/samples/ConnectionStringSettings_RetrieveFromConfig.cs

@@ -1,4 +1,6 @@
-using System;
+namespace ConnectionStringSettings_RetrieveFromConfig;
+
+using System;
 // <Snippet1>
 using System.Configuration;
 

doc/samples/ConnectionStringSettings_RetrieveFromConfigByName.cs

@@ -1,4 +1,6 @@
-using System;
+namespace ConnectionStringSettings_RetrieveFromConfigByName;
+
+using System;
 using System.Configuration;
 
 class Program

doc/samples/ConnectionStringSettings_RetrieveFromConfigByProvider.cs

@@ -1,4 +1,6 @@
-using System;
+namespace ConnectionStringSettings_RetrieveFromConfigByProvider;
+
+using System;
 using System.Data;
 using Microsoft.Data.SqlClient;
 using System.Configuration;

doc/samples/ConnectionStringsWeb_Encrypt.cs

@@ -1,4 +1,8 @@
-using System;
+/*
+#if NETFRAMEWORK
+namespace ConnectionStringsWeb_Encrypt;
+
+using System;
 using System.Configuration;
 using System.Web.Configuration;
 
@@ -35,3 +39,5 @@ static void ToggleWebEncrypt()
     }
     // </Snippet1>
 }
+#endif
+*/

doc/samples/ConnectionStrings_Encrypt.cs

@@ -1,4 +1,6 @@
-using System;
+namespace ConnectionStrings_Encrypt;
+
+using System;
 using System.Configuration;
 
 class Program
@@ -7,7 +9,7 @@ static void Main()
     {
     }
     // <Snippet1>
-    static void ToggleConfigEncryption(string exeFile)
+    static void ToggleConfigEncryption(string exeConfigName)
     {
         // Takes the executable file name without the
         // .config extension.