Implementation for `SeriesGroupBy`
Implementation for `SeriesGroupBy`

* Resolves #1114
* Uses `DataFrameGroupBy` object for implementation and squeeze the
  result to a Modin `Series` object after operator.
* Implementation overrides `__getattribute__` and intercepts method
  to apply and `squeeze` the return value before it is returned to the
  user

modin-project/modin,modin-project/modin