[Tags Feed] Lazy load tag rows

[thomashorta]

Fixes #20708

Add lazy loading to tag rows so the tag posts are only fetched when the tag component is rendered. This avoids loading content that might never be seen by the user.

Also move the execution of fetching the posts for tags to the IO dispatcher.

---

To Test:

1. Open Jetpack
2. Make sure the reader_tags_feed feature config is on
3. Go to the Reader
4. Go to the Tags feed
5. Verify the posts for the displayed tags are loaded
6. Scroll down
7. Verify the posts for tags that were offscreen show up in the loading state, then are loaded

---

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)

   • Updated unit tests that rely on loading posts for tags

---

PR Submission Checklist:

• I have completed the Regression Notes.
• 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.

---

Testing Checklist (strike-out the not-applying and unnecessary ones):

• WordPress.com sites and self-hosted Jetpack sites.
• Portrait and landscape orientations.
• Light and dark modes.
• Fonts: Larger, smaller and bold text.
• High contrast.
• Talkback.
• Languages with large words or with letters/accents not frequently used in English.
• Right-to-left languages. (Even if translation isn’t complete, formatting should still respect the right-to-left layout)
• Large and small screen sizes. (Tablet and smaller phones)
• Multi-tasking: Split screen and Pop-up view. (Android 10 or higher)

[wpmobilebot]

📲 You can test the changes from this Pull Request in WordPress by scanning the QR code below to install the corresponding build.

	App Name	WordPress
	Flavor	Jalapeno
	Build Type	Debug
	Version	pr20790-4acb2b9
	Commit	4acb2b9
	Direct Download	wordpress-prototype-build-pr20790-4acb2b9.apk

Note: Google Login is not supported on these builds.

[wpmobilebot]

📲 You can test the changes from this Pull Request in Jetpack by scanning the QR code below to install the corresponding build.

	App Name	Jetpack
	Flavor	Jalapeno
	Build Type	Debug
	Version	pr20790-4acb2b9
	Commit	4acb2b9
	Direct Download	jetpack-prototype-build-pr20790-4acb2b9.apk

Note: Google Login is not supported on these builds.

[codecov]

Codecov Report

Attention: Patch coverage is 74.54545% with 14 lines in your changes are missing coverage. Please review.

Project coverage is 40.78%. Comparing base (2a41ebc) to head (8067c7b).
Report is 1 commits behind head on feature/tags-ia.

❗ Current head 8067c7b differs from pull request most recent head 4acb2b9. Consider uploading reports for the commit 4acb2b9 to get more accurate results

Files	Patch %	Lines
...viewmodels/tagsfeed/ReaderTagsFeedUiStateMapper.kt	40.00%	6 Missing ⚠️
...der/viewmodels/tagsfeed/ReaderTagsFeedViewModel.kt	85.71%	4 Missing and 2 partials ⚠️
...droid/ui/reader/repository/ReaderPostRepository.kt	33.33%	2 Missing ⚠️

Additional details and impacted files

@@               Coverage Diff                @@
##           feature/tags-ia   #20790   +/-   ##
================================================
  Coverage            40.78%   40.78%           
================================================
  Files                 1493     1493           
  Lines                68611    68625   +14     
  Branches             11332    11333    +1     
================================================
+ Hits                 27984    27991    +7     
- Misses               38086    38093    +7     
  Partials              2541     2541           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[daniloercoli]

Left a minor comment, but other than that, it looks good to merge!

[sonarcloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

See analysis details on SonarCloud