Self-contained room monitoring sensors for CO2, temperature, and humidity on ESP32

ESP-IDF release/v4.3

• Controller: Wemos Lolin32 development board with embedded OLED display (branded HW-724, but any board of this nature should be suitable)
• CO2 sensor: MH-Z19B
• Temp/Hum sensor: DHT11

• Features
  • Add MQTT for remote monitoring
  • Configure embedded OLED for local sensor display
• Optimizations
  • Rework get_CO2 to not rely on vTaskDelay (event handler?)
  • Consider revisiting tasks one day?
  • Add 5 minute(+/-?) startup delay for CO2 - readings often invalid/frozen on boot
  • Identify source of occasional 1DegC/1%RH readings from DHT11.
    • Presumably Either bad hardware, or timeout/error return from library
    • If they're a fact of life, implement retry logic
• Documentation
  • Draw wiring diagram (/PCB layout?)
    • Design circuit/PCB/Enclosure to make this a self-contained USB dongle
  • Improve comments
  • Add instructions for dependencies
  • Add instructions for wifi parameter config (MenuConfig)