jbeam / pc language icons easy fix

[Sopze92]

Issue

1. Providing an icon-theme for jbeam/pc along with replacement icons for json/dae/images may be quite annoying
2. Package lacks the iconTheme contribution point for the icon-theme to work (or i'm too dumb, because I can't get your icons working at all)

Changes:

• Added the jbeam/pc icons as language-icons, which is a better option than to use an icon-theme
• Icons are now more BeamNG-ish, also included dark-mode icons

Pics

[angelo234]

Hmm I didn't realize that language icons could be set and the current ones before your commit don't seem to show for me also. So thanks for fixing it :)

[angelo234]

I think I'll delete the whole "beamng-icon-theme.json" file too.