Support projection coordinates in _read_ugrid

[kjnam]

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Proposed new feature or change:

The current _read_ugrid assumes the coordinate values are in longitude and latitude. and this not always true. https://github.com/UXARRAY/uxarray/blob/1c07b700e3b88212e9c12b6da34189c8aaafc38e/uxarray/io/_ugrid.py#L10-L25 The coordinates can be projected ones. So, I think it is better to rename coordinate variables only when the standard names of those are "longitude" and "latitude" following the CF convention. This behavior can be added easily without disturbing the current approach.