Add regular_ll_ml_grib2.tmpl to samples

[jsSvensson]

Is your feature request related to a problem? Please describe.

eccodes-python lacks the support to write hybrid level data on lat-lon grid to grib2 as the template file regular_ll_ml_grib2.tmpl is missing in the provided eccodes samples library (located e.g. here in a python environment: envs/myenv/share/eccodes/samples/). I assume many users prefers lat-lon representation of data as it e.g. is easy to project on Mercator or Plate Carree projection or as it plays well with e.g. xarray and cfgrib coordinate representation.

Describe the solution you'd like

Make a template file regular_ll_ml_grib2.tmpl and put it in the samples library in the downloaded eccodes dependency.

Describe alternatives you've considered

A workaround so far has been to create my own template from an existing hybrid level field on regular lat-lon grid and place it inte the envs/myenv/share/eccodes/samples/.

Additional context

No response

Organisation

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