Update common, Proxyguard support

[dzolnai]

• Updates the common library, changes some code that we now integrate correctly with the changes made in the library
• Adds support for Proxyguard. We need to use reflection here, because the Wireguard Go backend does not expose its VPN service, and we need that to protect our socket File Descriptor
• Renamed "Force TCP" to "Prefer TCP", to be inline with the API rename
• The app now notifies the common library about the VPN state changes
• Added crash handling for some edge cases, such as invalid WireGuard configs
• Improved the ProGuard config so that it does not obfuscate file names and line numbers