Add web based configuration at http://ip/preferences.html (WIP) (#117) (

#118) (#119)

* Update CO2_GADGET_REV to "014-web-config-new" in platformio.ini

* Add preferences page and handler for saving preferences

* Add onload function to fetch CO2, temperature, and humidity data

* Display Git HEAD in setup (Add .py and platformio_extra_configs.ini to .gitignore)

* Modify preferences.html

* Load preferences form (first version, non functional)

* Add ArduinoJson library and implement API endpoint to get preferences as JSON

* Preferences received on Save Preferences from configuration web page

* Update CO2_GADGET_REV to "020-web-config-new" in platformio.ini

* Update CO2_GADGET_REV to "024-web-config-new"

* Enable mDNS support for WiFi

* Increase size of DynamicJsonDocument in getPreferencesAsJson() function

* First rude web-config working (WIP no tested. no error checking)

* Enable utilityLoop() function in main loop

* Update publish functions to use int64_t and fix MQTT publish calls

* Add Restart ESP32 button to settings form. CSS styles

* Fix altitude misspelling

* Fix tempOffset assignment and update sensors

* Update vRef and battery voltage calculation on change from web settings page

* Add flash memory information to setup() function

* Fix utilityLoop()

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Co-authored-by: Mario Mariete <[email protected]>