INA226 JSON do not output leading spaces

[NorbertHD]

Description:

Closes #1691

Checklist:

• The pull request is done against the latest development branch
• Only one feature/fix was added per PR and the code change compiles without warnings
• I accept the DCO.

[1technophile]

I think the code could be simplified to have:

    INA226data["volt"] = (float)volt;
    INA226data["current"] = (float)current;
    INA226data["power"] = (float)power;

And get rid of the dtostrf

[NorbertHD]

1. Why cast to float? volt, current and power are already of type float.
2. With dtostrf you have exactly 2 decimal places. But with your proposal, you have rounding artifacts.
   e.g. 0.28 gets 0.280000001 or 3.43 gets 3.430000067 in the json data.

So how should we go on?

[1technophile]

1. The casting was a way to specify ArduinoJson the type, but it may not be necessary
   https://arduinojson.org/v6/api/config/use_double/

2. is it the responsibility of OMG to choose the number of decimals to display rather than the controller? Still trying to figure out this one. As it is use cases related, we could stick with the behavior of ZsensorHTU21, ZsensorLM75, ZsensorSHTC3, ZsensorDHT not rounding or round it like in ZsensorRN8209
   Open to discussion on this

[NorbertHD]

I have updated the PR, I think not rounding is the correct way. Data should be transported and stored in full precision and only rounded when displaying.

[1technophile]

Thanks