Improve VPN set-up to make it easier for users to select a country

[anthonypkeane]

Description Related to: brave/brave-ios#6499

Having the ability to select an exit point in a different country is a real plus for a VPN. Given some recent feedback (see Slack thread) we should rethink how we make this feature more easy to find.

Existing Country Selection Setting UI

[timchilds]

Figma

Here: https://www.figma.com/file/PqLTp3DnANLQMM1XzaChqZ/Mobile-VPN?type=design&node-id=3150%3A33941&mode=design&t=CB4RJ35FFPcvkXPf-1

And here: https://www.figma.com/file/PqLTp3DnANLQMM1XzaChqZ/Mobile-VPN?type=design&node-id=3803%3A56822&mode=design&t=cyHz7Bxt8KeIHYXk-1

[hffvld]

Verified on Pixel 2 XL, Galaxy Tab S8 and Pixel 7 using version(s):

Device/OS: 
- Pixel 2 XL / taimen-user  8.1.0 OPM2.171026.006.H1 release-keys
- Galaxy Tab S8 / gts8wifixx-user 13 TP1A.220624.014 release-keys
- Pixel 7 / panther_beta-user 14 AP21.240119.009 release-keys
Brave build: 1.63.149
Chromium: 121.0.6167.164 (Official Build) beta (64-bit) 

Filed follow-up issue #35939

STEPS:

1. Launch Brave
2. Purchase a VPN subscription
3. Enable VPN
4. Tree-dot menu > Country flag icon
5. Change to any other country > Verify

ACTUAL RESULTS:

• Verified that the country flag icon is not shown in the main menu when a user doesn't have an active VPN subscription
• Verified that the country flag icon is shown in the main menu when a user has an active VPN subscription
• Verified that switching to another country/region is working when using the country flag icon in the main menu

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Pixel 2 XL

1	2

Galaxy Tab S8

1	2

Pixel 7

1	2

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