Add emojis to Conversations

Ref. PWA14

NOTE: this feature is from a big development. See PWA discussion at GitHub.

Is your feature request related to a problem? Please describe.

As a registered participant when I’m having private Conversations with other participants I want to be able to express myself better.

Describe the solution you’d like

I want to have emojis in Conversations.

Additional context

We have already implemented this for Comments. See #7906

Acceptance criteria

• Given that I’m a participant,
  When I go to a new Conversation page
  Then I can add emojis.
• Given that I’m a participant that’s already having a Conversation
  When I go to this same Conversation page
  Then I can add emojis to my reply.