Fix bilinear resampling to areas with invalid coordinates

[pnuu]

The bilinear resampler didn't work for target areas that have invalid coordinates, like space pixels in the corners of full disk geostationary projections. This PR hopefully fixes this for data in xarray.DataArrays backed by dask arrays.

Tests are still needed.

• Closes Cannot resample with bilinear from lat/lon grid onto MSG full disk #422
• Tests added
• Tests passed
• Passes git diff origin/main **/*py | flake8 --diff

[codecov]

Codecov Report

Merging #423 (3da3aa4) into main (1928289) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main     #423   +/-   ##
=======================================
  Coverage   93.89%   93.89%           
=======================================
  Files          65       65           
  Lines       11130    11164   +34     
=======================================
+ Hits        10450    10482   +32     
- Misses        680      682    +2     

Flag	Coverage Δ
unittests	93.89% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
pyresample/bilinear/_base.py	95.74% <100.00%> (+0.04%)	⬆️
pyresample/bilinear/xarr.py	93.00% <100.00%> (+0.75%)	⬆️
pyresample/test/test_bilinear.py	100.00% <100.00%> (ø)
pyresample/ewa/dask_ewa.py	90.16% <0.00%> (-0.82%)	⬇️

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[coveralls]

Coverage increased (+0.001%) to 93.714% when pulling 3da3aa4 on pnuu:bugfix-bilinear-with-space-pixels into 1928289 on pytroll:main.

[djhoese]

LGTM