GH-11192 Move non-API OAuth endpoints from api4 to web package (#11327)

* GH-11192 WIP

* GH-11192 WIP

* GH-11192 tidy up

* GH-11192 rename handlers

* GH-11192 add TestAuthorizeOAuthApp

* GH-11192 WIP

* GH-11192 Tests mostly passing

* GH-11192 add missing closeBody function back

* GH-11192 add test api endpoint

* GH-11192 rename endpoint to oauth_test

web/web.go

@@ -33,6 +33,7 @@ func New(config configservice.ConfigService, globalOptions app.AppOptionCreator,
 		MainRouter:          root,
 	}
 
+	web.InitOAuth()
 	web.InitWebhooks()
 	web.InitSaml()
 	web.InitStatic()