Save calibration values on rover

[Ezward]

The esp32cam has the ability to write to SD card and to local flash memory. We should save calibration values that are sent to the rover in flash. We then also have to tell the web application what these values are when it asks, so we need an api for this.

• save calibration values to flash when the web application sends them to the rover.
• implement a web-socket api for asking for the calibration values. Design this so that the response may be used as a push value (at some point the rover may push these values over the web socket rather than waiting to be asked for them).