Introduce LatLngPoly and LatLngMultiPoly

[ajfriend]

Following from #332.

I'm leaving H3Shape instead of changing to just Shape because that seems too generic. And I think functions like geo_to_shape would be more confusing than geo_to_h3shape. Thoughts?

I'm also open to suggestions for a better name than H3Shape.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 100.00%. Comparing base (26285ef) to head (eec4c0f).

Additional details and impacted files

@@            Coverage Diff            @@
##            master      #364   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           10        10           
  Lines          319       319           
=========================================
  Hits           319       319           

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[ajfriend]

Gotta drops builds like https://github.com/uber/h3-py/pull/363