Added isTrial field to Constant
Reviewer: Dan Villafuerte
Added the following changes in the Study Details page of DataLoader Wizard:
• Step 1:  user can select from a list of existing studies, and this list also includes an "Add to New Study" option.
• Step 2: if "Add to New Study" option is selected, user is shown a text field to enter a name for the new study.

Issue: GCP-8431

Reviewer: Jaira
Merge remote-tracking branch 'remotes/origin/master_dev'