Fix ESP32 esp-idf OTA updates (#2424)

* WIP on separating out the OTA backends.

* Split off the individual OTA backends.

* Cleanup the three backends, split into .h and .cpp.

* After successfull flashing, activate the new boot partition.

* Fix linting issues.

* Minor cleanup

Co-authored-by: Maurice Makaay <mmakaay1@xs4all.net>
Co-authored-by: Otto winter <otto@otto-winter.com>

esphome/components/ota/ota_backend_arduino_esp32.h

@@ -0,0 +1,22 @@
+#pragma once
+#include "esphome/core/defines.h"
+#ifdef USE_ESP32_FRAMEWORK_ARDUINO
+
+#include "ota_component.h"
+#include "ota_backend.h"
+
+namespace esphome {
+namespace ota {
+
+class ArduinoESP32OTABackend : public OTABackend {
+  OTAResponseTypes begin(size_t image_size) override;
+  void set_update_md5(const char *md5) override;
+  OTAResponseTypes write(uint8_t *data, size_t len) override;
+  OTAResponseTypes end() override;
+  void abort() override;
+};
+
+}  // namespace ota
+}  // namespace esphome
+
+#endif  // USE_ESP32_FRAMEWORK_ARDUINO