[FR] Power switch that combines other power switches

### Is your feature request related to a problem? Please describe I have a printer using the Fysetc Hotkey Button panel, a USB powered set of buttons that control functions once klipper is running. I also have a GPIO controlled relay for powering the printer up. I have the GPIO Power config in Moonraker to turn on the relay. For reasons I don't understand the FIRMWARE_RESTART that fires when the relay is turned on doesn't reliably work with the Fysetc hotkeys. Sometimes it'll come up. Most of the time I must issue a second manual FIRMWARE_RESTART. This is annoying. I've discovered using uhubctl to shut down the Fysetc Hotkeys and power them up with the GPIO relay is much more reliable, but now I have two power switches I must flip every time. This is annoying. ### Describe the solution you'd like ```toml [power relay] type: gpio pin: gpio18 initial_state: off [power usb] type: uhubctl location: 2 initial_state: off [power printer_power] type: combined combine: relay, usb on_when_job_queued: True locked_while_printing: True restart_klipper_when_powered: True restart_delay: 2 ``` _Alternatively_, allow power plugins to 'follow' the state of another plugin. ```toml [power relay] type: gpio pin: gpio18 initial_state: off [power usb] type: uhubctl location: 2 initial_state: off follows: relay ``` ### Describe alternatives you've considered This can be automated in a variety of ways from the API, systemd unit shenanigans, etc. Having an inclusive-to-Moonraker-config would be a pleasant quality of life element. ### Additional information _No response_