Allow reactions to pass validations if they only have reaction SMILES

[skearnes]

• Adds a new option to ValidationOptions: allow_reaction_smiles_only
• When this is true (the default), reactions that have a REACTION_{CX}SMILES identifier, zero inputs, and zero outcomes will not be required to have inputs or outcomes. The other checks for e.g. provenance still apply.

[codecov[bot]]

Codecov Report

Merging #559 (ef17a25) into main (a84319e) will increase coverage by 0.10%. The diff coverage is 73.91%.

@@            Coverage Diff             @@
##             main     #559      +/-   ##
==========================================
+ Coverage   76.18%   76.29%   +0.10%     
==========================================
  Files          19       19              
  Lines        1894     1911      +17     
  Branches      463      468       +5     
==========================================
+ Hits         1443     1458      +15     
+ Misses        307      305       -2     
- Partials      144      148       +4     

Impacted Files	Coverage Δ
ord_schema/validations.py	68.69% <73.68%> (+0.07%)	:arrow_up:
ord_schema/message_helpers.py	84.84% <75.00%> (+0.65%)	:arrow_up:

[skearnes]

Thanks; PTAL.