VPN: Add support for custom DNS

[karlenDimla]

Task/Issue URL: https://app.asana.com/0/488551667048375/1207500898026382/f

Description

See attached task description

Steps to test this PR

https://app.asana.com/0/0/1207531536629227/f

[karlenDimla]

• #4671
• #4669
• #4652
• #4637 👈
• develop

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