Feature Request: Add idle_timeout 0 selection

[Kizime123]

I know people who never turn off their printer and always have it heating. Adding a idle_timeout timeout=0 call just doesn't work for klipper. Wondering if way to make it turned off or just set to 0 to turn off the feature?

[rogerlz]

feel free to test this PR https://github.com/DangerKlippers/danger-klipper/pull/165