Add boundary method to AreaDefinition and SwathDefinition

[ghiggi]

This PR adds the method boundary to AreaDefinition and SwathDefinition. It enables the correct retrieval of an AreaBoundary object, which in future will be used to interface with the new spherical interface.

• [x] Tests added
• [x] Tests passed
• [x] Passes git diff origin/main **/*py | flake8 --diff

[codecov[bot]]

Codecov Report

Merging #473 (2038dae) into main (ff0e843) will increase coverage by 0.06%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #473      +/-   ##
==========================================
+ Coverage   94.24%   94.31%   +0.06%     
==========================================
  Files          73       74       +1     
  Lines       12703    12855     +152     
==========================================
+ Hits        11972    12124     +152     
  Misses        731      731              

Flag	Coverage Δ
unittests	94.31% <100.00%> (+0.06%)	:arrow_up:

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

Impacted Files	Coverage Δ
pyresample/boundary.py	95.58% <100.00%> (+1.14%)	:arrow_up:
pyresample/geometry.py	87.40% <100.00%> (+0.23%)	:arrow_up:
pyresample/test/test_boundary.py	100.00% <100.00%> (ø)
pyresample/test/test_geometry.py	99.53% <100.00%> (+0.02%)	:arrow_up:

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[coveralls]

Coverage remained the same at 93.834% when pulling 2038dae8325da087c87e5215593b441b262b1edb on ghiggi:feature-area-boundary-method into ff0e843d2be264e88785542cb079a7e428405e33 on pytroll:main.

[ghiggi]

@djhoese is there something that I still need to address prior merging it?

[djhoese]

Waiting for merge of #475, then remerge of main into this branch, then tests to get updated and pass.

[djhoese]

Ok #475 is merged, can you merge main here and then update the test that needs it?

[ghiggi]

Ready to be merged