Remove reinitializing the BLE stack on each scan. (#949)

Using NimBLE requires less resources than bluedroid so it is much less beneficial to
deinitialize the stack. Instead this initializes it once in initial setup and only deinitializes
before entering deep sleep.

main/ZgatewayBT.ino

@@ -649,8 +649,6 @@ class MyAdvertisedDeviceCallbacks : public BLEAdvertisedDeviceCallbacks {
 void BLEscan() {
   disableCore0WDT();
   Log.notice(F("Scan begin" CR));
-  BLEDevice::setScanDuplicateCacheSize(BLEScanDuplicateCacheSize);
-  BLEDevice::init("");
   BLEScan* pBLEScan = BLEDevice::getScan();
   MyAdvertisedDeviceCallbacks myCallbacks;
   pBLEScan->setAdvertisedDeviceCallbacks(&myCallbacks);
@@ -660,7 +658,6 @@ void BLEscan() {
   BLEScanResults foundDevices = pBLEScan->start(Scan_duration / 1000, false);
   scanCount++;
   Log.notice(F("Found %d devices, scan number %d end deinit controller" CR), foundDevices.getCount(), scanCount);
-  BLEDevice::deinit(true);
   enableCore0WDT();
 }
 
@@ -713,7 +710,6 @@ void notifyCB(
  */
 void BLEconnect() {
   Log.notice(F("BLE Connect begin" CR));
-  BLEDevice::init("");
   for (vector<BLEdevice*>::iterator it = devices.begin(); it != devices.end(); ++it) {
     BLEdevice* p = *it;
     if (p->sensorModel == LYWSD03MMC || p->sensorModel == MHO_C401) {
@@ -819,10 +815,7 @@ void deepSleep(uint64_t time_in_us) {
 #    endif
 
   Log.trace(F("Deactivating ESP32 components" CR));
-  esp_bluedroid_disable();
+  BLEDevice::deinit(true);
-  esp_bluedroid_deinit();
-  esp_bt_controller_disable();
-  esp_bt_controller_deinit();
   esp_bt_mem_release(ESP_BT_MODE_BTDM);
   // Ignore the deprecated warning, this call is necessary here.
 #    pragma GCC diagnostic push
@@ -866,6 +859,9 @@ void setupBT() {
   atomic_init(&jsonBTBufferQueueNext, 0); // in theory, we don't need this
   atomic_init(&jsonBTBufferQueueLast, 0); // in theory, we don't need this
 
+  BLEDevice::setScanDuplicateCacheSize(BLEScanDuplicateCacheSize);
+  BLEDevice::init("");
+
   // we setup a task with priority one to avoid conflict with other gateways
   xTaskCreatePinnedToCore(
       coreTask, /* Function to implement the task */