Refresh calls may have side effects that need to be recorded if it
succeeds, especially common when when WaitForState is called from
resource.Retry.
If the WaitForState timeout is reached and there is a Refresh call
in-flight, wait up to refreshGracePeriod (set to 30s) for it to
complete.
Make sure that we can cancel the WaitForState refresh loop when reaching
a timeout, otherwise it may run indefinitely. There's no need to try and
store and read the Result concurrently, just pass the value over a
channel.
Sometimes when waiting on a target state, the set of valid states
through which a value will transition is unknown. This commit adds
support for an empty Pending slice and will treat any states that are not
the target as valid provided the timeouts are not exceeded.
The WaitForState method can't read the result values in a timeout
because they are still owned by the running goroutine. Keep all values
scoped inside the goroutine, and save them into an atomic.Value to be
returned.
Fixes race introduced in #8510
