Add full support for mmgg.feeder.petfeeder

[Wh1terat]

Pretty much started from scratch, new branch.

Decided to go with PetFeeder over PetFoodDispenser, neither is wrong but seemed more appropriate. All features now implemented (and one removed resetcleaner as not implemented device side..).

$ miiocli petfeeder --ip *snip* --token *snip* status
Food level: Normal
Feed plan: True
Food outlet: Ok
Food storage lid: Closed
Days until cleaning required: 10 day(s)
Days until desiccant replacement: 29 day(s)
WiFi status led: False
Dispense button lock: True

$ miiocli petfeeder --ip *snip* --token *snip* --help
Usage: miiocli petfeeder [OPTIONS] COMMAND [ARGS]...

Options:
  --ip TEXT     [required]
  --token TEXT  [required]
  --model TEXT
  --help        Show this message and exit.

Commands:
  add_feed_plan         Add Feed Plan.
  del_feed_plan         Delete Feed Plan.
  dispense_food         Dispense food.
  edit_feed_plan        Edit Feed Plan.
  get_feed_plans        Get feed plans.
  info                  Get (and cache) miIO protocol information from the...
  raw_command           Send a raw command to the device.
  reset_desiccant_left  Reset desiccant time.
  set_button_lock       Set button lock.
  set_feed_state        Set feed state.
  set_wifi_led          Set wifi led.
  status                Retrieve properties.
  test_properties       Helper to test device properties.

$ miiocli petfeeder --ip *snip* --token *snip* get_feed_plans
Slot: 04 Time: 08:30 Units: 8

Additional requirement for dataclasses backport package for Python <=3.6 (PEP 557)

Timezones in python are in general a mess. But looks to be semi resolved in PEP 615 but that's Python >=3.9 and no backport packages yet so opted just to keep with datetime for now and go between local time and china time which thankfully is fixed utc offset / does not follow DST.

I'm sure there will be bits that still don't quite adhere to your style 😄 but at this point it's got full functionality so happy for you to do whatever you feel best with it.

Oh and I did actually run tox this time 😅