nm-vpn script: awk-free + refactoring

[VKolegov]

Slightly more readable and easy-to-maintain version

• Expanded list of possibe connection names
• Dropped piping to awk (pure bash - less resources)

[kgilmer]

Thanks @VKolegov , looks good! Can you briefly mention how you tested? Did you test the case where no VPN connection is active?

[VKolegov]

@kgilmer Sure!

Here are 3 states(active connections) I was able to test (vpn, tun, no connection except wired ethernet)