Add v2 of the Hosting Service and build nuget packages for it (#675)

* Port v2 of Hosting service to SqlToolsService
- Renamed project to .v2 so that existing hosted service isn't impacted
- Copied over the CoreServices project which contains ConnectionServiceCore and other reusable services for anything interacting with MSSQL
- Ported unit test project across and verified tests run.

* Nuget package support for reusable DLLs

* Use 1.1 version per Karl's suggestion

* Use correct license URL and project URL

* Use new SMO packages

test/Microsoft.SqlTools.Hosting.UnitTests/UtilityTests/AsyncLockTests.cs

@@ -0,0 +1,49 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.SqlTools.Hosting.Utility;
+using Xunit;
+
+namespace Microsoft.SqlTools.Hosting.UnitTests.UtilityTests
+{
+    public class AsyncLockTests
+    {
+        [Fact]
+        public async Task AsyncLockSynchronizesAccess()
+        {
+            AsyncLock asyncLock = new AsyncLock();
+
+            Task<IDisposable> lockOne = asyncLock.LockAsync();
+            Task<IDisposable> lockTwo = asyncLock.LockAsync();
+
+            Assert.Equal(TaskStatus.RanToCompletion, lockOne.Status);
+            Assert.Equal(TaskStatus.WaitingForActivation, lockTwo.Status);
+            lockOne.Result.Dispose();
+
+            await lockTwo;
+            Assert.Equal(TaskStatus.RanToCompletion, lockTwo.Status);
+        }
+
+        [Fact]
+        public void AsyncLockCancelsWhenRequested()
+        {
+            CancellationTokenSource cts = new CancellationTokenSource();
+            AsyncLock asyncLock = new AsyncLock();
+
+            Task<IDisposable> lockOne = asyncLock.LockAsync();
+            Task<IDisposable> lockTwo = asyncLock.LockAsync(cts.Token);
+
+            // Cancel the second lock before the first is released
+            cts.Cancel();
+            lockOne.Result.Dispose();
+
+            Assert.Equal(TaskStatus.RanToCompletion, lockOne.Status);
+            Assert.Equal(TaskStatus.Canceled, lockTwo.Status);
+        }
+    }
+}

test/Microsoft.SqlTools.Hosting.UnitTests/UtilityTests/LoggerTests.cs

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+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System;
+using System.IO;
+using System.Linq;
+using Microsoft.SqlTools.Hosting.Utility;
+using Xunit;
+
+namespace Microsoft.SqlTools.Hosting.UnitTests.UtilityTests
+{
+    /// <summary>
+    /// Logger test cases
+    /// </summary>
+    public class LoggerTests
+    {
+       
+        /// <summary>
+        /// Test to verify that the logger initialization is generating a valid file
+        /// </summary>
+        [Fact]
+        public void LoggerDefaultFile()
+        {
+            // delete any existing log files from the current directory 
+            Directory.GetFiles(Directory.GetCurrentDirectory())
+                .Where(fileName 
+                     => fileName.Contains("sqltools_") 
+                     && fileName.EndsWith(".log", StringComparison.OrdinalIgnoreCase))
+                .ToList()
+                .ForEach(File.Delete);
+
+            Logger logger = new Logger();
+            // initialize the logger
+            logger.Initialize(
+                logFilePath: Path.Combine(Directory.GetCurrentDirectory(), "sqltools"),
+                minimumLogLevel: LogLevel.Verbose);
+
+            // close the logger
+            logger.Close();
+
+            // find the name of the new log file
+            string logFileName = Directory.GetFiles(Directory.GetCurrentDirectory())
+                .SingleOrDefault(fileName =>
+                    fileName.Contains("sqltools_")
+                    && fileName.EndsWith(".log", StringComparison.OrdinalIgnoreCase));
+                
+            // validate the log file was created with desired name 
+            Assert.True(!string.IsNullOrWhiteSpace(logFileName));
+            if (!string.IsNullOrWhiteSpace(logFileName))
+            {
+                Assert.True(logFileName.Length > "sqltools_.log".Length);
+                Assert.True(File.Exists(logFileName));
+
+                // delete the test log file
+                if (File.Exists(logFileName))
+                {
+                    File.Delete(logFileName);
+                }
+            }
+        }
+    }
+}