web-stories-wp: Valid link treated as invalid

Bug Description

Using a valid link (e.g. https://www.google.com) still triggers invalid link notification.

Expected Behaviour

No error message should be returned.

Steps to Reproduce

1. Insert element
2. Add link
3. Insert https://www.google.com as URL
4. See error message saying that the URL is invalid.

Screenshots

Additional Context

• Plugin Version: master
• Operating System:
• Browser:

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Acceptance Criteria

1. An error message is displayed below the input field if the URL is invalid.
2. The fields for the metadata (ie description and brand icon) should only appear if the user enters a valid url.

Implementation Brief