SmilesWidget: Canonicalize SMILES code

[danielhollas]

Canonicalize user-provided SMILES using RDKit. If the canonical name is different from the input SMILES, we print the canonical SMILES.

Test plan:

1. Input SMILES C=CC1=C(C2=CC=C(C3=CC=CC=C3)C=C2)C=C(C=C)C(C4=CC=C(C(C=C5)=CC=C5C(C=C6C=C)=C(C=C)C=C6C7=CC=C(C(C=C8)=CC=C8C(C=C9C=C)=C(C=C)C=C9C%10=CC=CC=C%10)C=C7)C=C4)=C1

should give you
C=Cc1cc(-c2ccc(-c3ccc(-c4cc(C=C)c(-c5ccc(-c6ccc(-c7cc(C=C)c(-c8ccc(-c9ccccc9)cc8)cc7C=C)cc6)cc5)cc4C=C)cc3)cc2)c(C=C)cc1-c1ccccc1

and should not fail.

I also add a missing error check that caused uncaught exception in #505

Closes #505. Closes #331

[codecov]

Codecov Report

Patch coverage: 80.00% and project coverage change: +0.02% 🎉

Comparison is base (5038966) 79.42% compared to head (94679cd) 79.44%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #507      +/-   ##
==========================================
+ Coverage   79.42%   79.44%   +0.02%     
==========================================
  Files          27       27              
  Lines        3757     3785      +28     
==========================================
+ Hits         2984     3007      +23     
- Misses        773      778       +5     

Flag	Coverage Δ
python-3.10	79.44% <80.00%> (+0.02%)	⬆️
python-3.8	79.48% <80.00%> (+0.01%)	⬆️
python-3.9	79.48% <80.00%> (+0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
aiidalab_widgets_base/structures.py	74.96% <71.42%> (-0.19%)	⬇️
tests/test_structures.py	100.00% <100.00%> (ø)

... and 1 file with indirect coverage changes

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[cpignedoli]

I tested in on my local instance and it works. It does not fix an open problem I have with a SMILE, that I never reported:
CC1=C(C)C(C2=C3C=CC4=C(C5=C(C)C(C)=C(C6=C(C=CC=C7)C7=CC8=C6C=CC=C8)C(C)=C5C)C9=CC=C%10N9[Fe]%11(N%12C(C=CC%12=C(C%13=C(C)C(C)=C(C%14=C(C=CC=C%15)C%15=CC%16=C%14C=CC=C%16)C(C)=C%13C)C%17=CC=C2N%17%11)=C%10C%18=C(C)C(C)=C(C%19=C(C=CC=C%20)C%20=CC%21=C%19C=CC=C%21)C(C)=C%18C)N43)=C(C)C(C)=C1C%22=C(C=CC=C%23)C%23=CC%24=C%22C=CC=C%24

[danielhollas]

@cpignedoli thanks for taking a look. Can you please open a new issue for this new SMILES?

Interestingly, in my application that generates multiple conformers it works. It looks like passing useRandomCoordinates into EmbedMolecule fixes the issue. But let's deal with that in a separate PR.

[yakutovicha]

The code looks good to me. Provided that @cpignedoli tested it, I approve 👍