Move unused forked code to external directory (#1192)

* Move unused forked code to external directory

* Fix SLN build errors

* Add back resource provider core since it's referenced by main resource provider project

* Update PackageProjects step of pipeline

external/Microsoft.SqlTools.DataProtocol.Contracts/ServerCapabilities/CompletionOptions.cs

@@ -0,0 +1,30 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+namespace Microsoft.SqlTools.DataProtocol.Contracts.ServerCapabilities
+{
+    /// <summary>
+    /// Defines completion options that the server can support
+    /// </summary>
+    public class CompletionOptions
+    {
+        /// <summary>
+        /// Most tools trigger completion request automatically without explicitly requesting it
+        /// using a keyboard shortcut (eg, ctrl+space). Typically they do so when the user starts
+        /// to type an identifier. For example if the user types 'c' in a JavaScript file, code
+        /// completion will automatically pop up and present 'console' besides others as a
+        /// completion item. Characters that make up identifiers don't need to be listed here.
+        /// 
+        /// If code completion should automatically be triggered on characters not being valid
+        /// inside an identifier (for example '.' in JavaScript) list them in this.
+        /// </summary>
+        public string[] TriggerCharacters { get; set; }
+        
+        /// <summary>
+        /// Server provides support to resolve additional information about a completion item
+        /// </summary>
+        public bool? ResolveProvider { get; set; }
+    }
+}