add platform for derived as folder part

[pindge]

Fixes: #298

addes platform abbrev to end of the dataset folder path if its c3 derivative product.

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.01 🎉

Comparison is base (17f80b6) 84.77% compared to head (9efe2c3) 84.78%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #299      +/-   ##
===========================================
+ Coverage    84.77%   84.78%   +0.01%     
===========================================
  Files           26       26              
  Lines         4408     4411       +3     
===========================================
+ Hits          3737     3740       +3     
  Misses         671      671              

Impacted Files	Coverage Δ
eodatasets3/names.py	95.26% <100.00%> (+0.04%)	⬆️

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[jeremyh]

As is discussed on Teams, the approval for this as a change is going through other channels, as eo-datasets is just following the upstream "naming conventions" documents that were made.

If it is approved, though, we should probably make this a different naming_conventions="blah" variant, rather than modfiying the existing one and breaking backwards compatibility. Products can then choose the move to the new one rather than have datasets start appearing in unexpected places.