Show a description when suggesting names

Fixes https://github.com/dotnet/roslyn/issues/19200

src/EditorFeatures/CSharpTest/Completion/CompletionProviders/DeclarationNameCompletionProviderTests.cs

@@ -3,6 +3,7 @@
 using System;
 using System.Collections.Immutable;
 using Microsoft.CodeAnalysis.Completion;
+using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.Completion.Providers;
 using Microsoft.CodeAnalysis.Diagnostics.Analyzers.NamingStyles;
 using Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.Completion.CompletionProviders;
@@ -36,7 +37,7 @@ public class MyClass
     MyClass $$
 }
 ";
-            await VerifyItemExistsAsync(markup, "MyClass", glyph: (int)Glyph.MethodPublic);
+            await VerifyItemExistsAsync(markup, "MyClass", glyph: (int)Glyph.MethodPublic, expectedDescriptionOrNull: CSharpFeaturesResources.suggested_name);
             await VerifyItemExistsAsync(markup, "myClass", glyph: (int)Glyph.FieldPublic);
             await VerifyItemExistsAsync(markup, "GetMyClass", glyph: (int)Glyph.MethodPublic);
         }

src/Features/CSharp/Portable/CSharpFeaturesResources.Designer.cs

@@ -20,7 +20,7 @@ namespace Microsoft.CodeAnalysis.CSharp {
     // class via a tool like ResGen or Visual Studio.
     // To add or remove a member, edit your .ResX file then rerun ResGen
     // with the /str option, or rebuild your VS project.
-    [global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Resources.Tools.StronglyTypedResourceBuilder", "4.0.0.0")]
+    [global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Resources.Tools.StronglyTypedResourceBuilder", "15.0.0.0")]
     [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
     [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]
     internal class CSharpFeaturesResources {
@@ -980,6 +980,15 @@ internal class CSharpFeaturesResources {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to (Suggested name).
+        /// </summary>
+        internal static string suggested_name {
+            get {
+                return ResourceManager.GetString("suggested_name", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to The name &apos;{0}&apos; does not exist in the current context..
         /// </summary>

src/Features/CSharp/Portable/CSharpFeaturesResources.resx

@@ -521,4 +521,7 @@
   <data name="Autoselect_disabled_due_to_member_declaration" xml:space="preserve">
     <value>Autoselect disabled due to member declaration</value>
   </data>
+  <data name="suggested_name" xml:space="preserve">
+    <value>(Suggested name)</value>
+  </data>
 </root>
\ No newline at end of file

src/Features/CSharp/Portable/Completion/CompletionProviders/DeclarationNameCompletionProvider.cs

@@ -191,7 +191,12 @@ private ITypeSymbol UnwrapType(ITypeSymbol type, Compilation compilation)
 
         CompletionItem CreateCompletionItem(string name, Glyph glyph, string sortText)
         {
-            return CommonCompletionItem.Create(name, CompletionItemRules.Default, glyph: glyph, sortText: sortText);
+            return CommonCompletionItem.Create(
+                name, 
+                CompletionItemRules.Default, 
+                glyph: glyph, 
+                sortText: sortText, 
+                description: CSharpFeaturesResources.suggested_name.ToSymbolDisplayParts());
         }
     }
 }