Add a local layer status icon in fastfetch

[castrojo]

We use an icon in the fastfetch to show when people are on a signed image. This is great because if you see a friend's flexing screenshot and you see a red X you can help them out.

We should offer something similar for when running in pure image mode.

Before sending a pull request please pitch your idea, it doesn't need to be in your face but noticeable for a user to notice. I think something akin to that warning light in your dashboard, but nothing too serious. It's like when my wife puts my car in comfort mode, it's not the end of the world but seriously we only drive in sport mode around here.

References:
https://github.com/ublue-os/bluefin/pull/1903/files

[tulilirockz]

I feel like it should be just a little red bubble on the right of the icon indicating to the user that there is something still wrong. If they get bothered enough by it theyll just search what the hell that is and how to remove it, kinda like the runtime safety exclamation point in front of your HSI level on fwupdmgr. Once they are on the pure image based mode they get a fancier icon instead of the lock icon, something cool, maybe image-specific (galaxy for Aurora, dino for Bluefin, controller for bazzite...).

[lem4s]

What about 🔏 (lock with pen) when using local layers instead of 🔐 on a pure image?
Other icons which would be fitting for images with local layers imho (ordered by my preference):
🛠️
🔺
🔸
♦️
🧩
❗
⭕
✒️
✏️
⛓️‍💥 (local layers) -> ⛓️ (pure images)