The VPNConfiguration parameter is opaque and tightly coupled to
TunnelKit. Connecting to a Profile makes infinitely more sense, beyond
simplifying the VPNManager class. Configuration building is fully
delegated to the strategy (as it has to be).
- VPNManager takes Profile and produces VPNConfigurationParameters
- VPNManagerStrategy takes VPNConfigurationParameters (abstract)
- TunnelKitVPNManagerStrategy takes VPNConfigurationParameters and
produces TunnelKitVPNConfiguration internally