Add support for Adafruit_DS3502

**Describe the problem you have/What new integration you would like**
Add support for the Adafruit DS3502 I2C Potentiometer library ,Thank you for your excelent job with ESPHome.

**Please describe your use case for this integration and alternatives you've tried:**
Use the DS3502 I2C Potentiometer to control Viridian EV EPC (cf: http://evbitz.uk/EVSE_Kit_-_Type_2_files/EPC%20Manual%20V1.2_050816.pdf ).
Viridian use a variable resistor to control output power for charging electic car

**Additional context**

spec here : https://github.com/adafruit/Adafruit_DS3502

Start by reviewing the linked Adafruit_DS3502 specification and the ESPHome feature-request discussion, then confirm how the DS3502 I2C potentiometer is intended to control the Viridian EV EPC. Done means ESPHome supports the DS3502 for the stated variable-resistance charging use case.

Written by the indexing model from the issue text.