std: Refactor the slice formatting code
std: Refactor the slice formatting code

Also fix the `*` specifier for more types, print an error message if we
can't show the value address.

raulgrell/zig,raulgrell/zig,raulgrell/zig,andrewrk/zig,andrewrk/zig,zig-lang/zig,zig-lang/zig,raulgrell/zig,raulgrell/zig,zig-lang/zig