Port Azure code from SSDT to the tools service (#477)

Porting of the vast majority of Azure-related code from SSDT. This is very large, so I want to put this out as one large "lift and shift" PR before I do the tools-service specific JSON-RPC service handlers, connect a new account handler (as the code to get necessary info from accounts and subscriptions isn't fully complete) and add tests over these

**What's in this PR**:

- Created 3 new projects:
  - Microsoft.SqlTools.ResourceProvider will host the executable that accepts requests for Azure-related actions over the JSON-RPC protocol. This must be separate from other DLLs since a direct dependency on the Azure SDK DLLs fails (they're NetStandard 1.4 and you can't reference them if you have RuntimeIdentifiers in your .csproj file)
  - Microsoft.SqlTools.ResourceProvider.Core is where all the main business logic is, including definitions and logic on how to navigate over resources and create firewall rules, etc.
  - Microsoft.SqlTools.ResourceProvider.DefaultImpl is the actual Azure implementation of the resource provider APIs. The reason for separating this is to support eventual integration back into other tools (since their Azure and Identity services will be different).
- Implemented the AzureResourceManager that connects to Azure via ARM APIs and handles creating firewall rule and querying databases. The dependent DLLs have had major breaking changes, so will need additional verification to ensure this works as expected
- Ported the unit tests for all code that was not a viewmodel. Viewmodel test code will be ported in a future update as we plumb through a service-equivalent to these. Also, the DependencyManager code which has overlap with our service provider code is commented out. Will work to uncomment in a future update as it has value to test some scenarios

**What's not in this PR**:
- Identity Services. We currently just have a stub for the interface, and even that will likely change a little
- anything JSON-RPC or registered service related. These will be adapted from the viewmodels and added in a separate PR

src/Microsoft.SqlTools.ResourceProvider.Core/Common/UserNeedsAuthenticationException.cs

@@ -0,0 +1,53 @@
+//
+// 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.Runtime.Serialization;
+
+namespace Microsoft.SqlTools.ResourceProvider.Core
+{
+    /// <summary>
+    /// The exception is used if any operation fails becauase user needs to reauthenticate 
+    /// </summary>
+    public class UserNeedsAuthenticationException : ServiceExceptionBase
+    {
+        /// <summary>
+        /// Initializes a new instance of the ServiceFailedException class.
+        /// </summary>
+        public UserNeedsAuthenticationException()
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the ServiceFailedException class with a specified error message.
+        /// </summary>
+        /// <param name="message">The error message that explains the reason for the exception. </param>
+        public UserNeedsAuthenticationException(string message)
+            : base(message)
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the ServiceFailedException class with a specified error message 
+        /// and a reference to the inner exception that is the cause of this exception.
+        /// </summary>
+        /// <param name="message">The error message that explains the reason for the exception. </param>
+        /// <param name="innerException">The exception that is the cause of the current exception, or a null reference 
+        /// (Nothing in Visual Basic) if no inner exception is specified</param>
+        public UserNeedsAuthenticationException(string message, Exception innerException)
+            : base(message, innerException)
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the ServiceFailedException class with serialized data.
+        /// </summary>
+        /// <param name="info">The SerializationInfo that holds the serialized object data about the exception being thrown.</param>
+        /// <param name="context">The StreamingContext that contains contextual information about the source or destination.</param>
+        public UserNeedsAuthenticationException(SerializationInfo info, StreamingContext context)
+            : base(info, context)
+        {
+        }
+    }
+}