Fix VIIRS L1B I-band angle names being inconsistent with VIIRS SDR

[djhoese]

While looking into #2258, it was pointed out that the I-band angle datasets in the viirs_l1b reader don't match the names in the viirs_sdr reader. This PR fixes that as well as refactors some of the yaml_reader.py to follow a top-to-bottom reading strategy (I got annoyed while debugging something).

• Closes VIIRS day_microphysics array broadcast error #2258
• Tests added

[codecov]

Codecov Report

Merging #2260 (88dfc5c) into main (05419d7) will increase coverage by 0.07%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #2260      +/-   ##
==========================================
+ Coverage   94.12%   94.20%   +0.07%     
==========================================
  Files         295      295              
  Lines       45376    45387      +11     
==========================================
+ Hits        42712    42756      +44     
+ Misses       2664     2631      -33     

Flag	Coverage Δ
behaviourtests	4.66% <6.97%> (-0.01%)	⬇️
unittests	94.85% <100.00%> (+0.03%)	⬆️

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

Impacted Files	Coverage Δ
satpy/readers/yaml_reader.py	97.50% <100.00%> (ø)
satpy/tests/reader_tests/test_viirs_l1b.py	100.00% <100.00%> (+1.06%)	⬆️
satpy/scene.py	93.37% <0.00%> (+0.15%)	⬆️
satpy/resample.py	79.56% <0.00%> (+0.16%)	⬆️
satpy/writers/mitiff.py	92.45% <0.00%> (+0.23%)	⬆️
satpy/readers/viirs_sdr.py	86.94% <0.00%> (+0.26%)	⬆️
satpy/tests/test_config.py	97.18% <0.00%> (+0.40%)	⬆️
satpy/readers/eps_l1b.py	83.62% <0.00%> (+0.43%)	⬆️
satpy/readers/seviri_l1b_native_hdr.py	100.00% <0.00%> (+0.57%)	⬆️
satpy/readers/mviri_l1b_fiduceo_nc.py	100.00% <0.00%> (+0.74%)	⬆️
... and 12 more

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[coveralls]

Coverage increased (+0.006%) to 94.8% when pulling 88dfc5c on djhoese:bugfix-viirsl1b-angle-names into 05419d7 on pytroll:main.

[mraspaud]

LGTM, thanks for cleaning up also!