Battery graph (Charge/discharge rate)

[FreezyLemon]

Checklist

• [X] I've looked through the documentation and existing open issues for this feature/feature request.

Describe the feature request

It would be nice to have a graph that shows the last X seconds of battery discharge rate in Watts, similar to battop. When charging, the graph should show the charging rate instead.

Maybe,this could even replace the current battery widget if all of the miscellaneous info can be integrated into the graph view (namely charge %, health %, time to empty).

[AlexanderMaxRanabel]

I'll make a fork probably