Remove obsolete global suppresions

Author: jcansdale

src/GitHub.Exports/GlobalSuppressions.cs

@@ -12,11 +12,11 @@ public interface IGitHubServiceProvider : IServiceProvider
         IServiceProvider GitServiceProvider { get; set; }
 
         T GetService<T>() where T : class;
-        Ret GetService<T, Ret>() where T : class
-                                 where Ret : class;
+        TRet GetService<T, TRet>() where T : class
+                                 where TRet : class;
 
         object TryGetService(Type t);
-        object TryGetService(string typename);
+        object TryGetService(string typeName);
         T TryGetService<T>() where T : class;
 
         void AddService(Type t, object owner, object instance);

src/GitHub.Exports/Services/IGitHubServiceProvider.cs

@@ -1,8 +1,10 @@
 using System;
 using System.Windows.Input;
+using System.Diagnostics.CodeAnalysis;
 
 namespace GitHub.Services
 {
+    [SuppressMessage("Microsoft.Performance", "CA1815:OverrideEqualsAndOperatorEqualsOnValueTypes")]
     public struct Notification
     {
         public enum NotificationType