When a user replies to a comment whose responses was hidden at the
moment of reply form submission and although the reply were correctly
added to the DOM it was hidden because was added to a collapsed list.
This solution is about showing all responses of parent comment after adding
the new comment to the DOM so the user can see new reply into the screen.
(This is not applicable to root comments which cannot be collapsed)
Extract the needed portion of code to a new partial to be able to update
only the elements needed when a new comment is added keeping UI properly
updated.
Tests are also a bit easier to read, even though we need to use the
`text:` option to find links because otherwise the text in the hidden
`<span>` tags will cause `click_link` to miss the link we want to click.
Here's an explanation by one of Capybara's authors:
https://github.com/teamcapybara/capybara/issues/2347#issuecomment-626373440
