CEF cookie fixes (#2934)

* Trying to get res:// and usr:// cookies to wrok

* Update CefGlue

* Bump CEF

* Seal types in WebView

Fixes warnings

* Move most of client cleanup to game thread.

This used to run in the windowing thread which broke CEF shutdown, most notably cookie saving.

* "flushcookies" command for CEF.

* Remove unecessary res:// code.

* Fix tests

* More request handler fixes.

* Good thing I don't have to care about commit quality in PRs like this.

Robust.UnitTesting/RobustIntegrationTest.cs

@@ -706,7 +706,8 @@ namespace Robust.UnitTesting
                 {
                     var client = Init();
                     GameLoop.Run();
-                    client.Cleanup();
+                    client.CleanupGameThread();
+                    client.CleanupWindowThread();
                 }
                 catch (Exception e)
                 {