Expand fenced emoji in reference expansion filter

What does this MR do and why?

!74369 (merged) introduced reference expansion, the feature where suffixing a #[Issue ID] or ![MR ID] with + (and later +s) expands the numerical text used in the link to the referenced Issuable to instead use the text of its title attribute. As implemented, however, this does not render and fenced emoji (:[emoji name]:) from being rendered, instead returning linked plain text.

This MR adds the step of using TanukiEmoji to find the fenced emoji and replace it in the text.

Related to #363663 (closed)