Add Solution maxLength

What does this MR do?

Adds a maxLength limit to vulnerabilities[].solution.

This limit is validated on the rails model.

It recently came-up as the reason for an error on the integration being done by an alliances partner.

While rejecting the whole report due to a single schema violation is not ideal, the existing error isn't helpful and leads to more questions: [IngestionError] Ingestion failed for some vulnerabilities.

What are the relevant issue numbers?

Checklist

• Ensure changes can be built upon without requiring a breaking change, see Building for Extensibility.
• Review and add/update tests for this feature/bug.
• Add an entry to the CHANGELOG if required, with the appropriate version. See Classifying Changes.
• Assign the MR to the appropriate person/people for review.