Add support for two FESOM grids

[dsarmany]

It is in the long-term plan at ECMWF to support interpolation and output on FESOM2 grids. For the upcoming climate-DT runs, it will suffice to support two grids: NG5 and CORE2.

For more information, please see FESOM geometry and FESOM uids.

[shahramn]

Why do these new ones not follow the convention of the others? i.e. they do not include the ORCA substring

[dsarmany]

These are not ORCA grids. They also do not follow the ARAKAWA staggering so we don't have a difference between U and V, etc. So Seb suggested we use different subtypes also.

If we can restrict what subtypes each type can take, it would be that NG5 and CORE2 would only be able to take these two subtypes (E, N).

[shahramn]

Added a JIRA for this:
https://jira.ecmwf.int/browse/ECC-1707

[codecov-commenter]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (7e82370) 80.80% compared to head (21e28ab) 80.80%.
Report is 46 commits behind head on develop.

Additional details and impacted files

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  Coverage    80.80%   80.80%           
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  Files          527      527           
  Lines        58490    58490           
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  Hits         47263    47263           
  Misses       11227    11227           

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[wdeconinck]

Please rename the "E" to "C", which is not confusing:
C for Cells, or Centres or Centroids is not confusing.
E could stand for Edges.