[iOS] Message vpn users about desktop vpn

[timchilds]

Summary

The desktop vpn and subscription linking will launch soon (date tbd). The marketing team would like to message existing mobile users who have already purchased a vpn subscription. Informing those users that they can now use their existing subscription to access the desktop vpn.

Design: https://www.figma.com/file/PqLTp3DnANLQMM1XzaChqZ/Mobile-VPN?node-id=2407%3A23999

UPDATE (01/09): Show the VPN popup on session 12 after upgrade. So that it does not clash with the Tab Bar popup going out in the same release.

[timchilds]

@Sam-Sibley here is where the subscription link button is on iOS:

And where it links to:

[timchilds]

@Sam-Sibley please add the figma design link.

[Sam-Sibley]

@timchilds Here is the figma link:
https://www.figma.com/file/PqLTp3DnANLQMM1XzaChqZ/Mobile-VPN?node-id=2407%3A23999

[timchilds]

Show the VPN popup on session 12 after upgrade. So that it does not clash with the Tab Bar popup going out in the same release.

[Uni-verse]

Verified on iPhone X running iOS 16.3.1 using version 1.49 (23.3.31.9)

Test Plan: #7101 (comment)

• Ensured that VPN link receipt callout is shown shortly after subscribing
• Ensured tapping on the callout link takes user to account.brave.com
• Ensured that tapping on the X will dismiss callout

Example	Example	Example

RPReplay_Final1680547485.mov