Validations for when the tenancy isn't demoted

When the user selects a non demoted tenancy and tries to fill
in the details as if it is a demoted tenancy
Checks for demoted tenancy verification

Added a second scenario in new claim generation, so that there is
a test for a claim with and without a demoted tenancy.
Merge pull request #133 from ministryofjustice/67999650/no-demoted-tenancy-validations

67999650/no demoted tenancy validations