Adjust the color of the cart icon to the icons core uses in the add field dialog

@majmunbog: So did we just use the same color than core?

Yes, we use the same color as core, but I've switched from loading the background image SVG to an inline SVG encoded as a data URL.

thank you for the fast fix @majmunbog! i've checked out your changes and the cart is now in line with the rest of the icons, so output wise this looks good:

and one note, there is currently work happening to improve the microcopy of the "add field" dialog modal (see 📌 [PP1] Refine field descriptions Active - comment #72 📌 [PP1] Refine field descriptions Active there lead me to install commerce and noticing the icon color issue as an aside). i'll open up follow up issues in the address and commerce queues as soon as there is a consensus and issue close to being fixed. cuz it would be good to adjust the micro copy for address and commerce field types to the patterns proposed for core as well (perhaps a style guide is needed after all as an artifact of 📌 [PP1] Refine field descriptions Active )