Evaluate Rust for Firmware on ESP32-C3

[bovi]

Consider the usage (toolchain, drivers, functionality) of Rust running on the ESP32-C3.

• flashing to ESP32-C3 is possible
• ap and station mode
• connection to Mindsphere via MQTT
• generation of Mindsphere certificate on-device

[bovi]

flashing to ESP32-C3 is possible

[bovi]

ap and station mode is also possible, see #1

[bovi]

certificate generation seems to have issues, see #11