Add FXIOS-12039 [Homepage] section viewed telemetry (backport #26234)

[mergify]

📜 Tickets

Jira ticket
Github issue

💡 Description

Replace item_viewed telemetry event (previous PR) with section_viewed labeled_counter.
Added a throttler to delay because when we scrollToTop it was still tracking impressions for the sections on the bottom when from the user perspectives they don't see those sections.
Separate logic for top sites items and sections.

Cases should be tested
For both new homepage + old homepage, impressions are triggered:
Load webpage -> tap on home button -> view homepage
Load webpage -> Add new tab from tab tray -> view homepage
Load webpage -> long pressing on tab tray to open new tab -> view homepage
Load webpage -> Add new tab from menu -> view homepage
Select homepage -> View webpage -> navigate back to homepage
Load webpage -> select on URL -> view homepage
On Homepage -> Add new tab from tab tray -> view homepage
On Homepage -> Add new tab from menu-> view homepage
Oh Homepage -> long pressing on tab tray to open new tab -> view homepage

Note: If on homepage, show modal (i.e. settings, menu), no impression is triggered

📝 Checklist

You have to check all boxes before merging

• Filled in the above information (tickets numbers and description of your work)
• Updated the PR name to follow our PR naming guidelines
• Wrote unit tests and/or ensured the tests suite is passing
• When working on UI, I checked and implemented accessibility (minimum Dynamic Text and VoiceOver)
• If needed, I updated documentation / comments for complex code and public methods
• If needed, added a backport comment (example @Mergifyio backport release/v120)

Video Capture

Telemetry_demo.mov

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This is an automatic backport of pull request #26234 done by [Mergify](https://mergify.com).

[mobiletest-ci-bot]

	Messages
📖	Project coverage: 34.61%
📖	Edited 12 files
📖	Created 1 files

Client.app: Coverage: 33.82

File	Coverage
Throttler.swift	91.67%	✅
TopSitesAction.swift	100.0%	✅
HomepageTelemetry.swift	98.28%	✅
TopSitesMiddleware.swift	94.07%	✅
HomepageViewController.swift	47.66%	⚠️
HomepageAction.swift	100.0%	✅
HomepageMiddleware.swift	100.0%	✅

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