Custom analyticsSource for the checkout web view when presented from All Domains flow

[salimbraksa]

Closes #21996

Description

This PR changes the analyticsSource value for the checkout web view when presented from the All Domains flow.

Test Instructions

Domain Only

1. Navigate to Me > All Domains then tap + button.
2. Search for a domain then select it.
3. Tap "Just buy a domain"
4. Expect the event webkitview_displayed <source: all_domains> to be logged in the console.

Existing Site

1. Navigate to Me > All Domains then tap + button.
2. Search for a domain then select it.
3. Tap "Existing wordpress.com site"
4. Select a site.
5. Expect the event webkitview_displayed <source: all_domains> to be logged in the console.

Regression

1. Navigate to My Site > Domains.
2. Search for a domain then select it.
3. Expect the event webkitview_displayed <source: domains_register> to be logged in the console.

Regression Notes

1. Potential unintended areas of impact
   The value of analyticsSource should be domains_register when presented from the My Site > Domains flow.

2. What I did to test those areas of impact (or what existing automated tests I relied on)
   None.

3. What automated tests I added (or what prevented me from doing so)
   None.

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 from this Pull Request in WordPress Alpha by scanning the QR code below to install the corresponding build.

	App Name	WordPress Alpha
	Configuration	Release-Alpha
	Build Number	pr22034-cc4be24
	Version	23.7
	Bundle ID	org.wordpress.alpha
	Commit	cc4be24
	App Center Build	WPiOS - One-Offs #7839

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[wpmobilebot]

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

	App Name	Jetpack Alpha
	Configuration	Release-Alpha
	Build Number	pr22034-cc4be24
	Version	23.7
	Bundle ID	com.jetpack.alpha
	Commit	cc4be24
	App Center Build	jetpack-installable-builds #6865

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[mokagio]

I'm going to bump this to the next release because we'll be code freezing 23.7 today and this hasn't been approved yet.

If this cannot wait two weeks and it's important that it makes it into this release, let me know and we'll organize a new beta once ready.

[hassaanelgarem]

Works as described 🚀

While you're at it, can you handle the TODO in RegisterDomainCoordinator.swift:L197? 🙏

[salimbraksa]

While you're at it, can you handle the TODO in RegisterDomainCoordinator.swift:L197? 🙏

Resolved in cc4be24.

N.B. I rebased this branch to release/23.7, so you might see old commits re-appearing in the activity feed again.

[salimbraksa]

If this cannot wait two weeks and it's important that it makes it into this release, let me know and we'll organize a new beta once ready.

@mokagio We would like this PR to be included in the version 23.7 but it doesn't require a new beta deployment as it doesn't add any new user-facing changes.