Adding BLE support for Eqiva Ble Smart Lock

**Describe the problem you have/What new integration you would like**
Integration for EQ3 HomeMatic smart lock
https://www.eq-3.com/products/homematic/detail/bluetooth-smart-lock.html

**Please describe your use case for this integration and alternatives you've tried:**
This is already working, it seems, but it's not ESPHome :)
https://github.com/tc-maxx/esp32-keyble/blob/master/src/main.cpp

**Additional context**
This is a good, cheap lock, impossible to integrate in Home assistant.
It would be much more useful with a proper integration

Start by reading the referenced esp32-keyble src/main.cpp and compare its BLE interaction with the requirements for an ESPHome integration. Confirm the supported lock operations and determine the integration entry points and tests needed; done means the Eqiva lock works through ESPHome in the requested use case.

Written by the indexing model from the issue text.