Blogging Prompts: Show prompts feature intro once when the tab controller is displayed

[wargcm]

See: #18429

Description

Displays prompts feature introduction screen a single time per install. Only displays in the following conditions:

• Nothing is presented by the selectedViewController or WPTabBarController
• The current blog is not self-hosted
• The user has not seen the intro view yet

Testing

To test:

• Enable bloggingPrompts feature flag in FeatureFlag.swift
• Launch the app and sign in using a WP site
• Navigate to the dashboard
• Verify the intro screen shows when:
  • No other screen was present
  • Landing on the dashboard
• Dismiss the intro screen
• Switch sites
• Verify the intro screen does not show
• Log out and back in with the same account
• Navigate to the dashboard
• Verify the intro screen does not show

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 pr18820-e80d1ac 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 pr18820-e80d1ac on your iPhone

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

[alpavanoglu]

QA Passed: ✅