This PR adds two missing tracks:

• When tapping "Write your first post": 🔵 Tracked: my_site_dashboard_card_item_tapped <default_tab_experiment: site_menu, sub_type: create_first, type: post>
• When tapping "Write your next post": 🔵 Tracked: my_site_dashboard_card_item_tapped <default_tab_experiment: site_menu, sub_type: create_next, type: post>

To test

1. Run the app
2. For a site without any posts, tap the "Write your first post" card
3. ✅ Make sure my_site_dashboard_card_item_tapped is fired with sub_type: create_first prop
4. Publish a post
5. Tap the "Write your next post" card
6. ✅ Make sure my_site_dashboard_card_item_tapped is fired with sub_type: create_next prop

Regression Notes

1. Potential unintended areas of impact
   n/a

2. What I did to test those areas of impact (or what existing automated tests I relied on)
   n/a

3. What automated tests I added (or what prevented me from doing so)
   n/a

PR submission checklist:

• I have completed the Regression Notes.
• I have considered adding unit tests for my changes.
• I have considered adding accessibility improvements for my changes.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.