Flexible varkeys in dfmt.preprocess_merge_meteofiles_era5()

[veenstrajelmer]

the varkey_list loop in dfmt.preprocess_merge_meteofiles_era5() only supports a limited set of meteo combinations. This should be more flexible. Better approach would be to:

• create a dictionary of abbreviations/quantities and remove the if-loop
• support for separate quantities, all should now be supported by the FM kernel since DIMRset 2.26.05 (8 dec 2023), consider adding a warning if not sticking to the four predefined combinations
• add backwards compatibility for combined quantities. Do notice the rainfall rate +-operand.
• test_preprocess_merge_meteofiles_era5_unsupported_varlist will fail since ["msl"] will not be unsupported anymore, so restructure this testcase

Old snippet of the code:

dfm_tools/dfm_tools/modelbuilder.py

Lines 208 to 225 in f6069de

	if varkey_list == ['msl','u10n','v10n','chnk']:
	forcing_meteo = hcdfm.ExtOldForcing(quantity='airpressure_windx_windy_charnock',
	filename=file_out,
	varname='msl u10n v10n chnk',
	filetype=hcdfm.ExtOldFileType.NetCDFGridData, #11
	method=hcdfm.ExtOldMethod.InterpolateTimeAndSpaceSaveWeights, #3
	operand=hcdfm.Operand.override, #O
	)
	ext_old.forcing.append(forcing_meteo)
	elif varkey_list == ['d2m','t2m','tcc']:
	forcing_meteo = hcdfm.ExtOldForcing(quantity='dewpoint_airtemperature_cloudiness',
	filename=file_out,
	varname='d2m t2m tcc',
	filetype=hcdfm.ExtOldFileType.NetCDFGridData, #11
	method=hcdfm.ExtOldMethod.InterpolateTimeAndSpaceSaveWeights, #3
	operand=hcdfm.Operand.override, #O
	)
	ext_old.forcing.append(forcing_meteo)