Read molecules from a SMILES file.
Examples
if (FALSE) { # is_installed_rdkit()
read_smiles(tidychem_example("smi-single.smi"))
read_smiles(tidychem_example("smi-multiple.smi"))
read_smiles(tidychem_example("smi-single-noname.smi"))
read_smiles(tidychem_example("smi-multiple-noname.smi"))
}