CMORizer for ESACCI-SEAICE

[axel-lauer]

Description

This PR adds downloading and formatting scripts for the ESACCI-SEAICE dataset version L4-SICONC-RE-SSMI-12.5kmEASE2-fv3.0. The scripts process daily and monthly mean sea ice concentration (siconc).

Checklist

• [🛠][1] This pull request has a descriptive title
• [🛠][1] Code is written according to the code quality guidelines
• [🛠][1] Documentation is available
• [🛠][1] Tests run successfully
• [🛠][1] The list of authors is up to date
• [🛠][1] Any changed dependencies have been added or removed correctly
• [🛠][1] All checks below this pull request were successful

New or updated data reformatting script

• [🛠][1] Documentation is available
• [🛠][1] The dataset has been added to the CMOR check recipe
• [🛠][1] The dataset has been added to the shared data pools of DKRZ and Jasmin by the @ESMValGroup/OBS-maintainers team
• [🧪][2] Numbers and units of the data look physically meaningful