Prometheus exporter for JBD BMS

Using library from https://github.com/fkressmann/python-jbdtool-bms

Known working devices

Overkill BMS https://overkillsolar.com/product/bms-100a-8s-lifepo4-12-2/ USB Module https://overkillsolar.com/product/usb-module-for-bms/