Provide means (result records schema) for external validators (e.g. NWB)

[yarikoptic]

Relates to already filed

• https://github.com/bids-standard/bids-validator/issues/1639

but main motivation for me ATM was to possibly integrate with

• nwb validator (in Python): https://pynwb.readthedocs.io/en/stable/validation.html - validates against base schema
• nwb inspector (in Python): https://github.com/NeurodataWithoutBorders/nwbinspector - also looks into data and might provide hints, also tune ups for specific use cases (e.g. for DANDI archive we require "subject" field being populated which is not required in schema)

in dandi-cli we already trying to unify results we obtain from nwb validate, nwb-inspector, bids schematools etc: ValidationResult https://github.com/dandi/dandi-cli/blob/master/dandi/validate_types.py#L29 with a number of uses/adaptors could be seen at in https://github.com/dandi/dandi-cli/blob/master/dandi/validate.py

[yarikoptic]

relates to attempt to review existing/relevant validators and their "results serialization":

• Please submit pointers to your validator output formats con/validation#1