[WIP] zephyr support for iotcloud

[andreagilardoni]

This PR aims to keep track of the effort of adding zephyr support for iotcloud.

This is currently being tested on a portentah7 with zephyr core at version https://github.com/andreagilardoni/ArduinoCore-zephyr/tree/iotcloud-integration.

Sketch is being built with link_mode=static arduino-cli compile -b arduino-git:ArduinoCore-zephyr:portentah7:link_mode=static

• Cloud Connection
• fix: <err> i2c_ll_stm32_v2: i2c: speed above "fast" requires manual timing configuration
• Ota
• link_mode=dynamic
• mqtt client using zephyr apis
• http client using zephyr apis
• test nicla
• test giga
• test opta
• test portentac33
• cleanup

Dependencies:

• https://github.com/andreagilardoni/Arduino_ConnectionHandler/tree/zephyr-support
• https://github.com/andreagilardoni/ArduinoECCX08/tree/zephyr-support
• https://github.com/pennam/ArduinoBearSSL/tree/zephyr
• https://github.com/andreagilardoni/Arduino_CloudUtils/tree/zephyr-support
• https://github.com/arduino-libraries/ArduinoMqttClient/tree/master
• https://github.com/arduino-libraries/Arduino_SecureElement/tree/main