Add testcase for refine_basegrid

[veenstrajelmer]

Todo:

• as below, but also check behavior for different types. It should work for int16 and float32, fails for int32 and float64
• Might not be necessary anymore after Support for float64 and int32 in GriddedSamples MeshKernelPy#146 is implemented (and unittest is added to mk refinement)

Start with something like this:

import xarray as xr
import dfm_tools as dfmt

# input
crs = 'EPSG:4326'

# domain and resolution
lon_min, lon_max, lat_min, lat_max = -68.55, -67.9, 11.8, 12.6
dxy = 0.05

# grid generation and refinement with GEBCO bathymetry
file_nc_bathy = r'http://opendap.deltares.nl/thredds/dodsC/opendap/deltares/Delft3D/netcdf_example_files/GEBCO_2022/GEBCO_2022_coarsefac08.nc'
data_bathy = xr.open_dataset(file_nc_bathy)
data_bathy_sel = data_bathy.sel(lon=slice(lon_min,lon_max),lat=slice(lat_min,lat_max))
data_bathy_sel["elevation"] = data_bathy_sel["elevation"].astype("int16")

# basegrid
mk_object = dfmt.make_basegrid(lon_min, lon_max, lat_min, lat_max, dx=dxy, dy=dxy, crs=crs)

# refine (fails if wrong type)
min_edge_size = 300 #in meters
dfmt.refine_basegrid(mk=mk_object, data_bathy_sel=data_bathy_sel, min_edge_size=min_edge_size)

# optional plot
import matplotlib.pyplot as plt
plt.close('all')
import contextily as ctx

fig, ax = plt.subplots()
mk_object.mesh2d_get().plot_edges(ax=ax,linewidth=1)
ctx.add_basemap(ax=ax, crs=crs, attribution=False)
dfmt.plot_coastlines(ax=ax, crs=crs)