Add criteria weighting 100% total validation
Add criteria weighting 100% total validation

Checks the criteria weighting sum if all criteria fields are set.
This relies on all three fields being required.

If the fields don't add up to a 100 an error is added for each field
that doesn't have any other validation errors.

alphagov/digitalmarketplace-api,alphagov/digitalmarketplace-api,alphagov/digitalmarketplace-api