Get time steps for a given datasetSource:
Get the time steps (in time_bp) available in a given dataset.
string defining dataset to be downloaded (a list of possible values can be obtained with
get_available_datasets()). If set to "custom", then a single nc file is used from "path_to_nc"
the path to the custom nc file containing the palaeoclimate reconstructions. All the variables of interest need to be included in this file.