Draft: Add a placeholder for inhibiting applications without a name in batterymonitor

I noticed that OBS “breaks” formatting in the battery monitor applet, because its application name isn't displayed before the colon.

Now, I can't tell whether that's the fault of OBS or PowerDevil, but since the applet's code already handles empty reasons, I figured this would belong here as well.

I'll need guidance on i18n, though. Should I add all combinations separately, using another level of ternary operators?

Two unrelated issues

• The videoconferencing software “zoom” has the icon “zoom” next to it, but that's not correct in this case.
• OBS doesn't show an icon at all. Maybe one could have a default icon so things align better?