This was failing quite often with the following error:
```
1) Emoji deny list when using composer should remove denied emojis from emoji picker
Failure/Error: find("#{COMPOSER_ID} .emoji-picker")
Capybara::ElementNotFound:
Unable to find css "#reply-control .emoji-picker"
```
This was because our `click_toolbar_button` call on the Composer
page object used a number for the position of the toolbar button,
which can be flaky since there are things that hide/show toolbar
buttons or change their position.
Each toolbar button in the composer has a CSS class, so it is
more reliable to use that instead. Also fixed an instance of
calling `has_X?` method directly instead of using the
`have_x` rspec matcher.
Responding to negative behaviour tends to solicit more of the same. Common wisdom states: "don't feed the trolls".
This change codifies that advice by introducing a new nudge when hitting the reply button on a flagged post. It will be shown if either the current user, or two other users (configurable via a site setting) have flagged the post.
This feature will allow sites to define which emoji are not allowed. Emoji in this list should be excluded from the set we show in the core emoji picker used in the composer for posts when emoji are enabled. And they should not be allowed to be chosen to be added to messages or as reactions in chat.
This feature prevents denied emoji from appearing in the following scenarios:
- topic title and page title
- private messages (topic title and body)
- inserting emojis into a chat
- reacting to chat messages
- using the emoji picker (composer, user status etc)
- using search within emoji picker
It also takes into account the various ways that emojis can be accessed, such as:
- emoji autocomplete suggestions
- emoji favourites (auto populates when adding to emoji deny list for example)
- emoji inline translations
- emoji skintones (ie. for certain hand gestures)
The latter can be called directly from the Topic page object,
so we can remove some duplication between the two. There are
levels of page objects (e.g. entire page, component, complete flow)
and its perfectly valid to call one from another.
