Fix instrument name reading from attributes for VIIRS L2 data

[pnuu]

The some of the attributes in the CSPP/ASCI files have been renamed between v3r0 and v3r2. The only on I've seen that affects Satpy is the instrument name. The original reader version was based on older data and works at least until v3r0 files, but the current one seems to handle only the newer files. With this PR both can be read.

• Closes #xxxx
• Tests added
• Fully documented
• Add your name to AUTHORS.md if not there already

[pnuu]

Any ideas what would be the best way to adapt the tests to check for both attribute versions? Dupplicating the fake filehandler class and the test class doesn't seem very attractive...

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.92%. Comparing base (85d9117) to head (2fff0d4).
Report is 34 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2760      +/-   ##
==========================================
- Coverage   95.94%   95.92%   -0.02%     
==========================================
  Files         375      377       +2     
  Lines       53293    53502     +209     
==========================================
+ Hits        51130    51321     +191     
- Misses       2163     2181      +18     

Flag	Coverage Δ
behaviourtests	4.10% <0.00%> (-0.02%)	⬇️
unittests	96.02% <100.00%> (-0.02%)	⬇️

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[pnuu]

Ok, duplicated the minimal amount of test code I thought was necessary.

[coveralls]

Pull Request Test Coverage Report for Build 8264934533

Details

• 35 of 35 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.003%) to 96.002%

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Totals
Change from base Build 8205996229:	0.003%
Covered Lines:	51193
Relevant Lines:	53325

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💛 - Coveralls

[djhoese]

CC @wjsharpe, Does this look good to you?

[djhoese]

Posting the realization from slack here for the record: @pnuu was using the old "viirs_l2.py" reader that he had created a while ago. A couple months ago I reworked all the VIIRS EDR (note EDR, not L2) to be one viirs_edr reader. The new VIIRS L2 reader being modified here is from #2740 by @wjsharpe and is for the NASA VIIRS L2 products not the NOAA EDR products.

[wjsharpe]

Looks good to me

[pnuu]

I should've remembered that viirs_l2 -> viirs_edr change. I'll test the v3r2 and v3r0 files tomorrow with the current Satpy and close this if both already work.

[pnuu]

Yeah, this PR was a mixup with the old viirs_l2.py and the current viirs_edr.py for the ASCI files. Closing, viirs_edr already works with both of the versions I have.