Add admin API to send trace notifications to registered (#7128)

Remove current functionality to log trace to file
using MINIO_HTTP_TRACE env, and replace it with
mc admin trace command on mc client.

cmd/server-main.go

@@ -290,6 +290,9 @@ func serverMain(ctx *cli.Context) {
 	// Init global heal state
 	initAllHealState(globalIsXL)
 
+	// initialize globalTrace system
+	globalTrace = NewTraceSys(context.Background(), globalEndpoints)
+
 	// Configure server.
 	var handler http.Handler
 	handler, err = configureServerHandler(globalEndpoints)