[feature] Free a little memory used by bluetooth if wifi is enabled or bluetooth is disabled (#10398)

* esp32: release BTDM heap when Bluetooth inactive

Release ESP-IDF BTDM memory after config load when Bluetooth is disabled or WiFi is enabled, recovering heap on ESP32 targets where BLE won’t be used for this boot.

* Address BT memory release review comments

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Co-authored-by: Ben Meadors <benmmeadors@gmail.com>

src/main.cpp

@@ -792,6 +792,11 @@ void setup()
     // We do this as early as possible because this loads preferences from flash
     // but we need to do this after main cpu init (esp32setup), because we need the random seed set
     nodeDB = new NodeDB;
+#ifdef ARCH_ESP32
+    // Config is loaded now, and Bluetooth has not been initialized yet. If the
+    // saved config will keep Bluetooth inactive, return its reserved memory early.
+    esp32ReleaseBluetoothMemoryIfUnused();
+#endif
 
     // Initialize transmit history to persist broadcast throttle timers across reboots
     TransmitHistory::getInstance()->loadFromDisk();