[Service Bus] isServiceBusError should not expose AmqpError which is an internal type

[ramya-rao-a]

In #12237, we introduced the ServiceBusError along with a helpful isServiceBusError() method. As discussed in #12237 (comment), the AmqpError type used here is internal to the package and the user need not be aware of it.

This issue is to track the work to not expose AmqpError to the user

[richardpark-msft]

One easy fix here is just to remove it altogether and accept AmqpError more broadly - we do a .name field check for ServiceBusError so it's unlikely that it'd get caught in our existing filter.

[chradek]

What about changing isServiceBusError to the following?

export function isServiceBusError(
  err: unknown
): err is ServiceBusError {
  return (err as Error | ServiceBusError)?.name === "ServiceBusError";
}

I'm not sure why we'd have to type err given this function is a type guard.

[ramya-rao-a]

That works for me