The front of course are disc.
There is a spring clip riveted to the backside of the inner brake pad that goes inside the caliper piston to hold things together during assembly. And there is a clip on the outer pad that anchors it to the caliper for the same reason.
The shims you are referring to in the second half of your question do exist. They come with certain brands of brake pads. Not everyone supplies them. And I think they come in different thicknesses. They are used to take up the slack from wear spots on the caliper rail. They simply snap in place and friction holds them there.
But there is no shim, clip, or spring from the factory other than the one on the pad.
Edit: I forgot that some disc brake set-ups use a spring clip to help stop the pads from rattling...
CLIP. Brake Caliper. .
CLIP, Anti-Rattle, SPRING.
Stock Code J3239865 Manufacturer Chrysler Categories Brakes > CHEROKEE, BRIARWOOD, GRAND CHEROKEE, COMANCHE; Brakes > CHEROKEE, WAGONEER, COMANCHE; Brakes > CJ; Brakes > Front Brakes; Brakes > WRANGLER, YJ; Brakes > XJ, MJ