Arduino IoT Collector: Add more internal metrics

Enhancement proposal

Release notes

Problem to solve

The Arduino IoT Collector does not parse all exposed metrics yet.

Environment information

• OS (Linux/Unix, macOS, Windows) and version: any
• Metrics type (Prometheus, file, Arduino, other hardware sensors): Arduino
• Building from source: Compiler and version (g++ --version, clang++ --version):

Proposal

Use the prepared Arduino Sketch in sensors/arduino-iot-collector/arduino on the Arduino Uno R4, and parse its output in the Arduino IoT Collector sensor app.