Blogging Prompts: Add dailyprompt tag to blogging prompt posts

[wargcm]

See: #18429

Description

Adds a dailyprompt tag to blogging prompt posts.

Testing

• Enable bloggingPrompts feature flag
• Login if necessary and navigate to 'My Site' tab

Prompts dashboard card:

• On the prompts card, tap on 'Answer Prompt'
• On the post editor, tap on the menu in the top right '...'
• Tap on 'Preview'
• Verify a dailyprompt tag exists on the post
• Close the editor

Prompts compact header view:

• Tap on the FAB '+'
• On the action sheet compact card, tap on 'Answer Prompt'
• On the post editor, tap on the menu in the top right '...'
• Tap on 'Preview'
• Verify a dailyprompt tag exists on the post
• Close the editor

Normal post:

• Tap on the FAB '+'
• Tap on 'Blog post'
• On the post editor, tap on the menu in the top right '...'
• Tap on 'Preview'
• Verify dailyprompt tag does not exist on the post

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.

[wpmobilebot]

You can test the changes in Jetpack from this Pull Request by:

• Clicking here or scanning the QR code below to access App Center
• Then installing the build number pr18851-6421260 on your iPhone

If you need access to App Center, please ask a maintainer to add you.

[wpmobilebot]

You can test the changes in WordPress from this Pull Request by:

• Clicking here or scanning the QR code below to access App Center
• Then installing the build number pr18851-6421260 on your iPhone

If you need access to App Center, please ask a maintainer to add you.

[alpavanoglu]

Tests:
✅ Prompts dashboard card
✅ Prompts compact header view
✅ Normal post

It didn't appear on one site I tested but I don't know the specifics of the site. If it is expected that it won't show on some themes/settings then we can merge