Add random_offset: to platform: sun

While I am aware that there are various techniques to add offset randomness relative to sunrise and sunset, it seems to me that implementing a native random offset would make sun automations significantly more simple.

An example of this enhancement:

    platform: sun
    # Possible values: sunset, sunrise
    event: sunset
    # Feature requested: random time offset. This example is - 30 minutes and +45 minutes.
    random_min: '-00:30:00'
    random_max: '00:45:00'

Thanks for your consideration and please VOTE if you like the idea.