Texas fans got a glimpse at what the future might look like with Arch Manning at quarterback in Saturday’s spring game. The redshirt freshman put together quite the performance to finish with 355 yards passing and three touchdowns, two of which were 75-yard bombs downfield. Manning’s final pass of the day — a Hail Mary — was intercepted as his team lost 35-34, but it was an encouraging performance that left many impressed. That included Longhorns coach Steve Sarkisian, who spoke on the performance from his young star postgame. “The biggest thing I saw from Arch was something we really harped o…