Adopt icon font in lightbulb actions

[miguelsolorio]

Related #78889

This adopts the icon font in editor and panel area for lightbulb actions:

And I also introduced two new color tokens for these, editor.lightbulbIcon.foreground and editor.lightbulbAutoFixIcon.foreground. When configured will look something like this:

cc @bpasero @aeschli

[aeschli]

@misolori Sorry for being late. I'd like to change the color id's to match the color naming style (2 segments: component.property)

editorLightBulb.foreground
editorLightBulb.autoFixForeground

Let me know if it's ok for you if I make the rename.

[miguelsolorio]

@aeschli don’t we need to imply it’s for the icon? The other color names include “icon”.

[aeschli]

As all there is an icon, why not just shorten it to 'LightBulp'?

[miguelsolorio]

I was leaning towards consistency across the other icon colors, but I’m ok shortening it to ‘LightBulb’. Feel free to make the change.