DRAFT: API for accessing partitioned connectivity, reworked topological aggregations

[philipc2]

Closes #980, #981

Overview

Expected Usage

import uxarray as ux

grid_path = "/path/to/grid.nc"
data_path = "/path/to/data.nc"

uxds = ux.open_dataset(grid_path, data_path)

# this is how you use this function
some_output = uxds.some_function()

# this is another way to use this function
other_output = uxds.some_function(some_param = True)