Add hover color to emoji icon

What does this MR do?

Adds hover color to emoji icon in discussions

Are there points in the code the reviewer needs to double check?

Shouldn't be

Why was this MR needed?

Keep consistency of color highlighting to indicate action icon

What are the relevant issue numbers?

Closes #20629 (closed)

Screenshots (if relevant)

Before: After:

Does this MR meet the acceptance criteria?

• CHANGELOG entry added
• Tests
  • All builds are passing
• Conform by the style guides
• Branch has no merge conflicts with master (if you do - rebase it please)
• Squashed related commits together