Draft: Move and share common bits with Symbolic Preview

By doing so, we are now loading the icons sheet similarly to how Symbolic Preview does. Except we cache the output and re-use it the future times. The next step would be to add an option to re-download the icons sheet, extract the icons & restart the app.

TODO:

• Ensure we haven't lost any functionalities
• Fix sorting of system icons
• Should we keep system icons at all in icon library?
• Should we also merge app icon preview here as well? it would allow us to share bits of code and most importantly give us -1 app to release.
• Move app icon preview icons rendering to libiconpreview
• Move recents items popover to libiconpreview
• Build a simple CLI app on top of libiconpreview, maybe?

Closes #11