[Feature Request] Implement ESP32 Unified OTA support

[skgsergio]

Until now, I've been using in my ESP32 WiFi nodes a build of the former WifiOTA firmware for ESP32 + p espota.py`. But now that this was superseded by the Unified OTA, the web flasher even flashes the ota partition with the new firmware.

So the --reboot-ota no longer works as it expects a different message format, including the file hash, and the espota.py seems to no longer work as the protocol is different.

Would it be possible to include the functionality in the python library and CLI so we can flash without the Android app? I have several DIY nodes, and it's a pain having to send the firmware to my phone first.

Reference: meshtastic/Meshtastic-Android#4095