Add an ability to create a fixed lat/lon grid

[mgrover1]

As discussed in #1412

^{Originally posted by wxwolff April 6, 2023}
Can pyart be used to create a fixed lat, lon grid (e.g. 0.1° x 0.1°), rather than just a fixed (x,y) grid?

It would be great if the Py-ART gridding functionality supported gridding to some regular lat/lon (ex. 0.1 x 0.1 degree) grid, as opposed to some fixed x/y coordinate grid.