Add tests to improve code coverage (#187)

* DbColumn and ReliableConnection tests

* More retry connection tests

* More tests

* Fix broken peek definition integration tests

* Fix test bug

* Add a couple batch tests

* Add some more tests

* More tests for code coverage.

* Validation and Diagnostic tests

* A few more tests

* A few mote test changes.

* Update file path tests to run on Windows only

src/Microsoft.SqlTools.ServiceLayer/Connection/ReliableConnection/AmbientSettings.cs

@@ -48,12 +48,12 @@ namespace Microsoft.SqlTools.ServiceLayer.Connection.ReliableConnection
         internal const string DoNotSerializeQueryStoreSettingsIndex = "DoNotSerializeQueryStoreSettings";
         internal const string AlwaysEncryptedWizardMigrationIndex = "AlwaysEncryptedWizardMigration";
 
-        private static readonly AmbientData _defaultSettings;
+        internal static AmbientData _defaultSettings;
 
         static AmbientSettings()
         {
             _defaultSettings = new AmbientData();
-        }
+        }       
 
         /// <summary>
         /// Access to the default ambient settings.  Access to these settings is made available

src/Microsoft.SqlTools.ServiceLayer/Connection/ReliableConnection/ReliableConnectionHelper.cs

@@ -801,7 +801,7 @@ namespace Microsoft.SqlTools.ServiceLayer.Connection.ReliableConnection
             public string DatabaseName;
         }
 
-        private static bool TryGetConnectionStringBuilder(string connectionString, out SqlConnectionStringBuilder builder)
+        internal static bool TryGetConnectionStringBuilder(string connectionString, out SqlConnectionStringBuilder builder)
         {
             builder = null;
 

src/Microsoft.SqlTools.ServiceLayer/Connection/ReliableConnection/ReliableSqlCommand.cs

@@ -235,7 +235,7 @@ namespace Microsoft.SqlTools.ServiceLayer.Connection.ReliableConnection
                 return _command;
             }
 
-            private void ValidateConnectionIsSet()
+            internal void ValidateConnectionIsSet()
             {
                 if (_connection == null)
                 {

src/Microsoft.SqlTools.ServiceLayer/Connection/ReliableConnection/RetryLimitExceededException.cs

@@ -34,5 +34,12 @@ namespace Microsoft.SqlTools.ServiceLayer.Connection.ReliableConnection
     [Serializable]
     internal sealed class RetryLimitExceededException : Exception
     {
+        internal RetryLimitExceededException() : base()
+        {            
+        }
+
+        internal RetryLimitExceededException(string m, Exception e) : base(m, e)
+        {
+        }
     }
 }

src/Microsoft.SqlTools.ServiceLayer/Connection/ReliableConnection/RetryPolicy.cs

@@ -292,7 +292,7 @@ namespace Microsoft.SqlTools.ServiceLayer.Connection.ReliableConnection
         }
         */
 
-        private static int? GetErrorNumber(Exception ex)
+        internal static int? GetErrorNumber(Exception ex)
         {
             SqlException sqlEx = ex as SqlException;
             if (sqlEx == null)