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/ClientCapabilities/TextDocument/Completion.cs

@@ -0,0 +1,63 @@
+//
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+//
+
+using Microsoft.SqlTools.DataProtocol.Contracts.Common;
+
+namespace Microsoft.SqlTools.DataProtocol.Contracts.ClientCapabilities.TextDocument
+{
+    /// <summary>
+    /// Capabilities specific to the 'textDocument/completion' request
+    /// </summary>
+    public class CompletionCapabilities : DynamicRegistrationCapability
+    {
+        /// <summary>
+        /// Client supports these CompletionItem specific capabilities. Can be <c>null</c>
+        /// </summary>
+        public CompletionItemCapabilities CompletionItem { get; set; }
+            
+        /// <summary>
+        /// Client supports these CompletionItemKinds as responses to completion requests
+        /// </summary>
+        public CompletionItemKindCapabiltities CompletionItemKind { get; set; }
+    }
+    
+    public class CompletionItemCapabilities
+    {
+        /// <summary>
+        /// Whether client supports snippet formats as completion results
+        /// </summary>
+        /// <remarks>
+        /// A snippet can define tab stops and placeholders with <c>$1</c>, <c>$2</c> and
+        /// <c>${3:foo}</c>. <c>$0</c> defines the final tab stop, it defaults to the end of
+        /// the snippet. Placeholders with equal identifiers are linked, that is typing in one
+        /// will update others, too.
+        /// </remarks>
+        public bool? SnippetSupport { get; set; }
+            
+        /// <summary>
+        /// Whether client supports commit characters on a completion item
+        /// </summary>
+        public bool? CommitCharactersSpport { get; set; }
+            
+        /// <summary>
+        /// Client supports these content formats for the documentation property. The order
+        /// describes the preferred format of the client. May be <c>null</c>
+        /// </summary>
+        public MarkupKind[] DocumentationFormat { get; set; } 
+    }
+        
+    public class CompletionItemKindCapabiltities
+    {
+        /// <summary>
+        /// Completion item kind values the client supports. When this property exists, the
+        /// client also guarantees that it will handle values outside its set gracefully and
+        /// falls back to a default value when unknown.
+        /// 
+        /// If this property is not present, the client only supports the completion item kinds
+        /// from Text to Reference as defined in the initial version of the protocol.
+        /// </summary>
+        public CompletionItemKinds? ValueSet { get; set; }
+    }
+}