Function once

once(
    event:
        | "willLaunch"
        | "didLaunch"
        | "didTerminate"
        | "didHide"
        | "didUnhide"
        | "didActivate"
        | "didDeactivate",
    listener: (app: HSApplication | null) => void,
): void
Register a listener that fires at most once for an application event.
Parameters
- event:
      | "willLaunch"
      | "didLaunch"
      | "didTerminate"
      | "didHide"
      | "didUnhide"
      | "didActivate"
      | "didDeactivate"
  The event to listen for
- listener: (app: HSApplication | null) => void
  Called the next time a matching event occurs, then automatically removed
Returns void