isConnectedToNetwork() always returned false on ARCH_PORTDUINO because none of HAS_WIFI, HAS_ETHERNET, or USE_WS5500 are defined for Linux native builds. This caused wantsLink() to always return false, preventing the MQTT thread from ever connecting at boot. Fix: return true for ARCH_PORTDUINO since Linux always has network access available. Co-authored-by: Jonathan Bennett <jbennett@incomsystems.biz>