Consistent Ids between subsets

[wpreimes]

ISMN_Interface.get_dataset_ids are different when a different subset (network) is initialized. Would be better if they are consistent with the global dataset

i.e. The following IDs should be identical

ds = ISMN_Interface(".../FRM4SM/07_data/ismn_data/ISMN_v202301/extracted/", network=['WEGENERNET', 'SMOSMANIA'])
ids = ds.get_dataset_ids('soil_moisture', 0, 10, filter_meta_dict={'network': 'WEGENERNET'})
print(ids)

>> [215, 216, 220, 221, 225, 226, 231, 234, 238, 242, 244, 248, 250, 253, 256, 258, ... 

ds = ISMN_Interface(".../FRM4SM/07_data/ismn_data/ISMN_v202301/extracted/", network=['WEGENERNET'])
ids = ds.get_dataset_ids('soil_moisture', 0, 10, filter_meta_dict={'network': 'WEGENERNET'})
print(ids)

>> [2, 3, 7, 8, 12, 13, 18, 21, 25, 29,..