Adafruit Seesaw (as an expander)

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

I'd like to have the option to use the Adafruit Seesaw boards to expand GPIO for mutiple different outputs via I2C. INcluding firmware option for default configuration, or even the alternate firmware to use I2C to UART

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

One of the main issues is I wanted a way to have 4 UARTs on a ESP32, so that I can use SIM800L, GPS, DF Player, and an OBD2 to UART unit from Sparkfun, but I have tried to find alternatives, and since Automatic dissolved a while back, I have been trying to look for a native Home Assistant way to track a few things using OBD2. (different Integration request).

**Additional context**

https://cdn-learn.adafruit.com/downloads/pdf/adafruit-seesaw-atsamd09-breakout.pdf?timestamp=1606670773

Start with the linked Adafruit Seesaw ATSAMD09 breakout PDF and compare its I2C GPIO and alternate I2C-to-UART capabilities with the requested ESP32 use case. Define the supported board or firmware configuration and expected UART expansion behavior; the issue is ready when those requirements and a concrete integration scope are agreed.

Written by the indexing model from the issue text.