Warn about applications potentially draining battery when running on battery

### Problem

Some apps need more compute power than others - for example, watching 4K videos with VLC media player or other applications like Oracle VirtualBox or comparable apps.

I often run into a situation where I have a few VMs still running in the background when amd I take my laptop, close the lid and then when I'm on the train, I just take out the laptop, open the lid again to do some writing on libreoffice. But I already forgot about the VMs still running in the background.

They often use precious battery capacity and suddenly I realize my battery is almost empty

### Proposal

When battery mode is detected, show notifications when either

* certain known battery hungry apps are running (like Video Players actively playing videos, running VMs with KVM, VMWare, Oracle, etc.
* Average CPU usage is staying high for more than a few seconds

### Prior Art (Optional)

_No response_