Pajamas guidance: Using emojis in UI text

Emojis are sometimes used in celebratory UI text when there's a positive outcome, however we currently don't have specific guidelines on how and when to use emojis in UI text.

This issue proposes that the guidelines in Pajamas be updated to state emojis should be reserved for celebratory text only.

We should also investigate if there are any implications for localization - are all emojis universal or can they mean different things in different countries and cultures. Are they open to interpretation? (The 🙏 is sometimes interpreted as a high-five) If so, we should consider limiting emojis to ones that are universal.