[Reader Improvements] Show "View in browser" and "Share" actions in reader post details toolbar

[RenanLukas]

Fixes #19729

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To Test:

1 - Install JP and sign in
2 - Open reader
3 - Tap on any post in any tab
4 - Verify that the "View in browser" and "Share" actions are shown in the toolbar
5 - Verify that both actions work as expected, including their analytics events. The analytics event for share action was changed and should look like this:

Tracked: item_shared_reader, Properties: {"blog_id":123,"feed_id":123,"follow":true,"source":"post_detail_toolbar"}

Discussion: p1701731047457609/1701688108.191079-slack-C01CW1VMLAF

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Regression Notes

1. Potential unintended areas of impact
   None

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

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

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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.

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UI Changes Testing Checklist:

• 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]

	1 Warning
⚠️	PR is not assigned to a milestone.

Generated by 🚫 Danger

[thomashorta]

The changes look good to me and everything is working as expected! Thanks!

[thomashorta]

Nice! 👏🏼

[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	pr19731-9a3e8e6
	Commit	9a3e8e6
	Direct Download	jetpack-prototype-build-pr19731-9a3e8e6.apk

Note: Google Login is not supported on these builds.

[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	pr19731-9a3e8e6
	Commit	9a3e8e6
	Direct Download	wordpress-prototype-build-pr19731-9a3e8e6.apk

Note: Google Login is not supported on these builds.