Custom add to Power menu

### Feature Description

I'd like to be able to have a completely custom entry on the Power menu. For example, run a script or perform an action for options not already provided. The mechanism to do this per currently provided option completely exists in a really elegant way, I just want the ability to add one myself.

### Use Case

For just my use case, if you change EFI boot options to restart it would be great to have an option to boot from a different UEFI drive on next boot. i.e. efibootmgr -n

### Compositor(s)

All compositors

### If Other, please specify

_No response_

### Proposed Solution

_No response_

### Alternatives/Existing Solutions

_No response_