Add current_resistor and voltage_divider configuration to CSE7766 platform

**Describe the problem you have/What new integration you would like**

The CSE7766 platform should have options to configure the values for current_resistor and voltage_divider. (Similar to the one for HLW8012)

**Please describe your use case for this integration and alternatives you've tried:**

The current implementation assumes that all devices using the CSE7766 chip use the default values for the current sense resistor and the voltage divider resistor as proposed in the data sheet.

Devices like the Blitzwolf SHP5 or the Gosund SP112 (at least in some markets) use different resistors. You will get very wrong values for voltage and power with the default.

Mine uses two 953kΩ resistors in series (1906 kΩ) for voltage sensing. The current code assumes 1 MΩ.

You could work around it with calibrations but that is a time consuming process. It would be way better to fix the root cause and we would have simple pair of values to share with others with the same device to fix their values. Also: You would need calibrations for power, voltage and current.