Investigate rewrite of OTA functions

[johnwalicki]

The firmware currently uses the official Espressif ESP32 OTA functions.
https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/system/esp_https_ota.html

The official OTA functions has some limitations. We cannot OTA upgrade the SPIFFS data partition. That might be a blocker if we need to refresh the server certificates.

There are several other open source libraries that provide OTA functionality. Investigate which is best for the OpenEEW use case.

• https://github.com/bitfocus/esp-ota#methods
• https://github.com/chrisjoyce911/esp32FOTA

[andygrillo]

OTA with SPIFFS is now working in AWS version. However we have omitted OTA from the main to make it easier to get started. Can we close this issue?