[#58694284] Added TaxonConceptSourceValidation Rule. And seed
[#58694284] Added specs for TaxonConceptSourceValidationRule
Merge branch 'develop' into species_source_code_validation
Annotated model
[#58694284] Added serializer to TaxonConceptSourceValidationRule. Squished species_name and source_code
[#58694284] actually squish_null is indexed
Merge pull request #94 from unepwcmc/species_source_code_validation

Species source code validation
Merge branch 'develop' into rename_taxon_concept_code_pairs