Validates that hostLabel traits are applied correctly for operation inputs.
 
     - Validates that if an operation's endpoint hostPrefix has labels
     then it must have input.
- Validates that a corresponding top-level input member can be found
     for each label in each operation endpoint hostPrefix.
- Validates that the correct type target type and traits are used for
     labels.
- Validates that all labels in the endpoint hostPrefix of each
     operation have corresponding hostLabel traits.
- Validates that an expanded version of each endpoint hostPrefix of
     each operation is a valid RFC 3896 host.
- Validates that the host prefix SHOULD end in a period if it contains
     host labels.