Compute the split info on the given files.

Compute the split info (num shards, num examples,...) metadata required by tfds.folder_dataset.write_metadata.

See documentation for usage:

out_dir Output directory where to save the metadata. It should be available from the apache beam workers. If not set, apache beam won't be used (only available with some file formats).
filename_template filename template of the splits. The template should have set the data_dir because this is used to compute the split info.

split_infos The list of tfds.core.SplitInfo.