Insert favorites when bookmark is favorite and no index

[jotaemepereira]

Task/Issue URL: https://app.asana.com/0/1201048563534612/1208595122638622/f
Tech Design URL:
CC:

Description:
It fixes new bookmarks not being added to favorites from the dialog when no favorites index is passed.

Steps to test this PR:

1. Create new bookmark from the dialog or by going to the new tab page and tapping the add favorite cell
2. Check the ‘Add as favorite’ box
3. Add the bookmark
4. The bookmark should be part of the new tab page array of favorites (you should also check is a favorite in the panel and in the bookmarks manager)

Definition of Done:

• Does this PR satisfy our Definition of Done?

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