Add support for Sense-U BLE Baby Monitor

**Describe the problem you have/What new integration you would like**
Add an integration to read values from the Sense-U Baby Monitor (https://www.products.sense-u.com/baby) - a BLE button. This is a small button that clips to a baby's clothes to monitor breathing rate, position and temperature and transmits this information via BLE. It is designed to work with a smartphone app but that limits range to being close to the smartphone.

**Please describe your use case for this integration and alternatives you've tried:**
It would be great if an ESP32 running ESPHome could listen to the messages from the device and provide the information as three sensors to Home Assistant for monitoring a baby remotely or to use as an input to automations either within the ESP32 device or in HA.

**Additional context**
The plan I would suggest adopting for this sensor would be similar to the Xiaomi sensors that are available already and very close indeed to the Ruuvi Tag sensor that is currently in development. I have already scanned the BLE messages that are produced by the device and have found that a given UUID notifies on each update of a sensor result. I am currently decoding how the information in this is stored and that can be used as input to the integration. I'm happy to start writing the integration based on the Ruuvi Tag implementation in the dev channel.