End of Year: Hide the share button for the intro/epilogue views

[emilylaguna]

📘 Project: #376

This hides the share button on the first and last story views.

To test

1. Launch the app
2. Go to Profile > Tap End of Year card
3. ✅ Verify the Share button is hidden on the first view
4. Tap through the next stories, and ✅ verify they all show the share button
5. ✅ Verify the Share button works and you're able to share the assets
6. ✅ Verify the shared assets are correct for each story
7. Go to the last view
8. ✅ Verify the Share button is hidden

Checklist

• I have considered if this change warrants user-facing release notes and have added them to CHANGELOG.md if necessary.
• I have considered adding unit tests for my changes.
• I have updated (or requested that someone edit) the spreadsheet to reflect any new or changed analytics.

[jgcaruso]

Refactor looks good and tests as expected! Share button isn't rendered on first or last story. Share button continues to work on middle stories and shares the correct image.