Why this change?
We have been seeing tests failures due to errors like
```
Capybara::ElementNotFound:
Unable to find css "#topic-footer-button-assign"
```
when running our system tests in CI. However, I can't quite figure out
why that is happening and have invested way too much time to do so.
Therefore, I'm trying to fix this by closing a topic via the topic
timeline controls instead of the footer button instead.
The goal is to add a class so when assigns are not public, their descriptions can be styled similar to whispers... this is a light way to reassure admins of assign message visibility.
The previous behavior was:
1. Assign a topic to someone
2. Close the topic with the setting unassign_on_close enabled
3. Assign the topic to the same user as before
This caused small broken or empty posts to be displayed.
This commit also introduces system specs
Jarek Radosz
Joffrey JAFFEUX
Alan Guo Xiang Tan
Martin Brennan
Kris
Jan Cernik