Added warning message to be displayed when specifying environments in the trait donors query

GCP-10048

Reviewer: Crisjaira Villarino
Added checking if the traitsList is not empty before moving to the next screen (specify environments).
Show warning message to the user if the traitsList is empty.

GCP-10048

Reviewer: Crisjaira Villarino
Added jUnit cases to test PreselectTraitFilter functions before moving to the specify environment screen

GCP-10048

Reviewer: Crisjaira Villarino