[UDP] Sandbox test account passwords are displayed and transmitted in plain text

After install and configuring the UDP package, the user will be able to add Sandbox Test Accounts via the UDP Settings asset. Currently when configuring a Sandbox Test Account, the test account's password will be displayed and transmitted in plain-text.

Steps to reproduce:
- In Unity 2019.3, create a new project and nstall the Universal Distribution Portal (UDP) package (alternatively download the attached project)
- Menu: Window > Universal Distribution Portal > Settings
-Inspector (UDP Settings) > Register the project with Unity Cloud Services if the UDP Settings Inspector pane indicates it is not already
- Inspector (UDP Settings) > UDP Sandbox Test Accounts > Add new test account
- Observe when entering a password, the password is displayed in plain text
- (Optional) with a packet sniffer attached, push the Sandbox Test Accounts observing the data is transmitted in a plain-text field (aside from TLS) -- should this be a hash?