Add antimeridian helpers to utils

[gadomski]

Related Issue(s): n/a

Description:
Includes some new helper functions:

• normalize: returns a new Polygon that has all of its longitudes in the same sign, even if this means going beyond -180 or 180.
• split: returns a new MultiPolygon that contains polygons on either side of the antimeridian, per the GeoJSON recommendations.
• fix_item: applies these change to an Item's geometry, inplace

PR checklist:

• Code is formatted (run scripts/format).
• Code lints properly (run scripts/lint).
• Tests pass (run scripts/test).
• Documentation has been updated to reflect changes, if applicable.
• Changes are added to the CHANGELOG.

[pjhartzell]

Looks good. There is an edge case where it does not work as expected: polygons enclosing the north or south pole. Perhaps add that caveat in the docstring and put that down as a TODO.

[gadomski]

@pjhartzell done in f31524f.

[gadomski]

Converting to draft until I implement the functionality described in stactools-packages/landsat#13 (comment).

[gadomski]

@pjhartzell I've added fix_item if you want to take a look.

[lossyrob]

I was expecting the behavior to be that if a geometry was more "westernly" than "easternly", then the normalization would use negative numbers instead of positive. E.g.

def test_item_fix_antimeridian_normalize_west(self) -> None:
        canonical = Polygon(
            ((170, 40), (170, 50), (-140, 50), (-140, 40), (170, 40)))
        item = Item("an-id",
                    geometry=shapely.geometry.mapping(canonical),
                    bbox=canonical.bounds,
                    datetime=datetime.datetime.now(),
                    properties={})
        antimeridian.fix_item(item, antimeridian.Strategy.NORMALIZE)
        expected = shapely.geometry.box(170, 40, 190, 50)
        assert shapely.geometry.shape(item.geometry).equals(expected)
        assert item.bbox
        assert list(item.bbox) == [-190.0, 40.0, -140.0, 50.0]

This would allow e.g. STAC queries that are asking for western areas to pick up the appropriate geometries. As it stands it looks like anything that crosses the antimeridian from the west will get labeled as a very east polygon.

[gadomski]

@lossyrob done in d8b9d41.

[lossyrob]

Couple of small suggestions, but besides the known TODO this LGTM