Add getDonorStatus to DonorBackingForm

(set as @JsonIgnore)
Add auto-populated fields to DonorBackingForm

(set to JsonIgnore)
Add getBloodGroup() to DonorBackingForm

(set to JsonIgnore)
Rename PreferredContactMethod to ContactMethodType

Renamed in DonorBackingForm to be consistent across Donor,
DonorViewModel & DonorBackingForm.
Update DonorViewModel donorPanel to return panel ID

This makes it simpler to handle Donor updates, by representing Donor
Panels by their ID, rather than a donorPanel object. Need to assess if
it would be better to return the donorPanel name, rather than the ID.