[BREAKING] - Refactor NimBLEScan

* General code cleanup
* `NimBLEScan::start` will no longer clear cache or results if scanning is already in progress.
* `NimBLEScan::clearResults` will now reset the vector capacity to 0.
* `NimBLEScan::stop` will no longer call the `onScanEnd` callback as the caller should know its been stopped when this is called.
* `NimBLEScan::clearDuplicateCache` has been removed as it was problematic and only for the esp32. Stop and start the scanner for the same effect.
* `NimBLEScan::start` takes a new bool parameter `restart`, default `true`, that will restart an already in progress scan and clear the duplicate filter so all devices will be discovered again.
* Scan response data that is received without advertisement first will now create the device and send a callback.
* Added new method: `NimBLEAdvertisedDevice::isScannable()` that returns true if the device is scannable.
* Added default callbacks for `NimBLEScanCallbacks`
* `NimBLEScanCallbacks` function signatures updated:
* - `onDiscovered` now takes a `const NimBLEAdvertisedDevice*`
* - `onResult` now takes a `const NimBLEAdvertisedDevice*`
* - `onScanEnd` now takes a `const NimBLEScanResults&` and `int reason`
* Added new erase overload: `NimBLEScan::erase(const NimBLEAdvertisedDevice* device)`
* `NimBLEScanResults::getDevice` methods now return `const NimBLEAdvertisedDevice*`
* `NimBLEScanResults` iterators are now `const_iterator`

examples/basic/BLE_scan/main/main.cpp

@@ -21,7 +21,7 @@ int scanTime = 5 * 1000; // In milliseconds, 0 = scan forever
 BLEScan* pBLEScan;
 
 class MyAdvertisedDeviceCallbacks: public BLEAdvertisedDeviceCallbacks {
-    void onResult(BLEAdvertisedDevice* advertisedDevice) {
+    void onResult(const BLEAdvertisedDevice* advertisedDevice) {
       printf("Advertised Device: %s \n", advertisedDevice->toString().c_str());
     }
 };
@@ -35,7 +35,7 @@ void scanTask (void * parameter){
         pBLEScan->clearResults();   // delete results fromBLEScan buffer to release memory
         vTaskDelay(2000/portTICK_PERIOD_MS); // Delay a second between loops.
     }
-    
+
     vTaskDelete(NULL);
 }