Resolve "Convert UTF-8 Emoji to Gitlab emoji"

What does this MR do?

Convert unicode emojis to images.

Why was this MR needed?

For better cross platform interoperability with emojis.

Does this MR meet the acceptance criteria?

• CHANGELOG entry added
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #22591 (closed)