Support ticker-tasks as methods on modules rather than requiring separate implementing classes.

[scr-oath]

The motivational use-case for this is to add multiple tickers for a module. By including a RunnerFunc as an implementer of Runner, this will allow, for instance something like this:

type MyModule struct {}

func (m *MyModule) RunOneTask() error {
    // do something
    return nil
}

func (m *MyModule) RunAnotherTask() error {
    // do something else
    return nil
}

func BuildMyModule(_ json.RawMessage, _ moduledeps.ModuleDeps) (interface{}, error) {
    ret := &MyModule{}
    task.NewTickerTask(1 * time.Minute, runner.RunnerFunc(ret.RunOneTask))
    task.NewTickerTask(2 * time.Minute, runner.RunnerFunc(ret.RunAnotherTask))
    return ret, nil
}