Front end validation for allowlist email adding

[arorasomya]

Describe the bug
The add button on the email allowlist page, adds any space, blank emails. Add validation on the frontend for email.

To Reproduce
Steps to reproduce the behavior:

1. Create a drive
2. Go to postico and make the drive private by putting 'True' for the 'private' field
3. Click on 'manage' to go to the drive page
4. Don't type anything, just click 'add'
5. see that an empty row was added

Expected behavior
Empty row/blanks should not be added

Screenshots