minor cleanup proposal (#4169)

* MESHTASTIC_EXCLUDE_WIFI and HAS_WIFI cleanup...
Our code was checking HAS_WIFI and the new MESHTASTIC_EXCLUDE_WIFI
flags in various places (even though EXCLUDE_WIFI forces HAS_WIFI
to 0).  Instead just check HAS_WIFI, only use EXCLUDE_WIFI inside
configuration.h

* cleanup: use HAS_NETWORKING instead of HAS_WIFI || HAS_ETHERNET
We already had HAS_NETWORKING as flag in MQTT to mean 'we have
tcpip'.  Generallize that and move it into configuration.h so that
we can use it elsewhere.

* Use #pragma once, because supported by gcc and all modern compilers
instead of #ifdef DOTHFILE_H etc...

---------

Co-authored-by: Jonathan Bennett <jbennett@incomsystems.biz>

src/sleep.cpp

@@ -17,7 +17,7 @@
 #ifdef ARCH_ESP32
 #include "esp32/pm.h"
 #include "esp_pm.h"
-#if !MESHTASTIC_EXCLUDE_WIFI
+#if HAS_WIFI
 #include "mesh/wifi/WiFiAPClient.h"
 #endif
 #include "rom/rtc.h"
@@ -56,7 +56,7 @@ RTC_DATA_ATTR int bootCount = 0;
  */
 void setCPUFast(bool on)
 {
-#if defined(ARCH_ESP32) && !MESHTASTIC_EXCLUDE_WIFI
+#if defined(ARCH_ESP32) && HAS_WIFI
 
     if (isWifiAvailable()) {
         /*