Issue with enter key when adding a filter list via URL

Environment

• current release ABP 3.6.2 (modal window), UI release 2019-1 (popover)
• Opera and Chrome

Steps to reproduce

1. Open Advanced tab in desktop settings page
2. Click on the 'Add filter list via URL button' if reproducing with UI release-2019-1 or 'Add a new filter list', if reproducing with the latest ABP release
3. Paste/write a valid filter list in the input field, such as https://testpages.adblockplus.org/en/abp-testcase-subscription.txt
4. Press 'Enter'
5. OBSERVE: the modal windows/popover closes and the filter list is not added
6. Reopen the modal window/popover
7. Add the valid filter list in the input field again
8. Press 'Enter'
9. OBSERVE: nothing happens

Expected behavior

I would expect that pressing 'Enter' will close the modal/popover and add the filter list to the table.

Additional info

In Firefox, pressing the 'Enter' key in all cases above has no effect.

Hints for testers

This change also touches on the other parts of that dialog so we need to check that the entire dialog (including the button that opens it) still works.