Let applications control when scale-to-zero is allowed

Scale-to-zero is currently based on a cooldown period. This means If the application is performing a background task, which is running after the response has been send to the last request, the background task will be canceled if it takes too long.

It would be desirable to be able to disable/enable scale-to-zero from the application to allow background tasks to finish.

This would be achieved using a pseudofs controls, e.g.:

import "fmt"

func main() {
  // echo 1 > /sys/kraftcloud/scale-to-zero
  _ = os.WriteFile("/sys/kraftcloud/scale-to-zero", []byte{"1\n"}, 0644)
}

and via our native SDKs e.g.

import (
  kcp "github.com/kraftcloud/go-sdk/platform"
)

func main() {
  _ = kcp.ScaleToZero()
}