[GUI] wrong app icon used in macOS stage manager

During testing the previous RC release @mcnair found that the RiseupVPN app was showing the Bitmask app icon in macOS stage manager, as seen in the following screenshot.

Turns out different branded builds of the App had the same CFBundleIdentifier in the Plist.Info file leading to using the wrong icon.

this occurs when you have the Bitmask branded client and the RiseupVPN client both are installed on macOS, since the Bitmask branded client is not released to public in any manner users are unlikely to face this issue