Fix add contacts on campaign builder

[nupuragrahari]

The add contacts feature on the campaign builder page is broken.

The popup closes the moment you type a letter in the input box.
The pop up should not close until the name of the list and atleast 1 contact has been added.
If these inputs have not been added the fields should show an error when trying to Save the list.
The user can click on the cross to exit the popup

[nupuragrahari]

@yryuvraj please pick this up.

To reproduce:

1. Go to campaigns.
2. Click on Open builder for a campaign
3. Click on the Add contacts button in the builder page
4. Try to input info and saving list