ARCSpecies does not show atom labels for the mol object if it was generated from a `species_dict`

Describe the bug
ARCSpecies does not show atom labels for the mol object if it was generated from a species_dict

How to reproduce

>>> from arc.species import ARCSpecies
>>> spc = ARCSpecies(label="fail", smiles="CC")
>>> for index, atom in enumerate(spc.mol.atoms):
...     atom.label = str(index)
... 
>>> new_spc = ARCSpecies(species_dict=spc.as_dict())
>>> print([atom.label for atom in new_spc.mol.atoms])
['', '', '', '', '', '', '', '']

even though the species_dict does have atom labels:

'mol': {'atoms': [{'element': {'number': 6, 'isotope': -1},
    'radical_electrons': 0,
    'charge': 0,
    'label': '0',
    'lone_pairs': 0,
    'id': -27544,
    'props': {'inRing': False},
    'atomtype': 'Cs',
    'edges': {-27543: 1.0, -27542: 1.0, -27541: 1.0, -27540: 1.0}},
   {'element': {'number': 6, 'isotope': -1},
    'radical_electrons': 0,
    'charge': 0,
    'label': '1',
    'lone_pairs': 0,
    'id': -27543,
    'props': {'inRing': False},
    'atomtype': 'Cs',
    'edges': {-27544: 1.0, -27539: 1.0, -27538: 1.0, -27537: 1.0}},
   {'element': {'number': 1, 'isotope': -1},
    'radical_electrons': 0,
    'charge': 0,
    'label': '2',
    'lone_pairs': 0,
    'id': -27542,
    'props': {'inRing': False},
    'atomtype': 'H',
    'edges': {-27544: 1.0}},
   {'element': {'number': 1, 'isotope': -1},
    'radical_electrons': 0,
    'charge': 0,
    'label': '3',
    'lone_pairs': 0,
    'id': -27541,
    'props': {'inRing': False},
    'atomtype': 'H',
    'edges': {-27544: 1.0}},
   {'element': {'number': 1, 'isotope': -1},
    'radical_electrons': 0,
    'charge': 0,
    'label': '4',
    'lone_pairs': 0,
    'id': -27540,
    'props': {'inRing': False},
    'atomtype': 'H',
    'edges': {-27544: 1.0}},
   {'element': {'number': 1, 'isotope': -1},
    'radical_electrons': 0,
    'charge': 0,
    'label': '5',
    'lone_pairs': 0,
    'id': -27539,
    'props': {'inRing': False},
    'atomtype': 'H',
    'edges': {-27543: 1.0}},
   {'element': {'number': 1, 'isotope': -1},
    'radical_electrons': 0,
    'charge': 0,
    'label': '6',
    'lone_pairs': 0,
    'id': -27538,
    'props': {'inRing': False},
    'atomtype': 'H',
    'edges': {-27543: 1.0}},
   {'element': {'number': 1, 'isotope': -1},
    'radical_electrons': 0,
    'charge': 0,
    'label': '7',
    'lone_pairs': 0,
    'id': -27537,
    'props': {'inRing': False},
    'atomtype': 'H',
    'edges': {-27543: 1.0}}],

(see the 'labels' on the atom list)
Expected behavior
return the same labels.

Additional context
Accurate parsing of the species object is important for restarts and for testing, as they help to avoid obsolete callings of other functions while performing tests, which may cause unrelated failures.
😄

Start in the arc.species ARCSpecies initialization path that handles species_dict and reconstructs mol.atoms, then reproduce the example using ARCSpecies.as_dict(). Confirm that the reconstructed atom labels match the labels in species_dict and verify the same behavior with a focused test or rerun of the provided example.