Draft: vkd3d: Allow positional printf specifiers in vkd3d_string_buffer_printf.

Positional printf specifiers are a POSIX extension, and Microsoft doesn't let you use them in the normal printf function. The first commit lets you use positional specifiers by wiring up the Microsoft printf-family calls.

The next commit changes some intrinsics that we implement as HLSL code to use the new positional specifiers; this deduplicates a lot of code and means you don't have to go counting through a million type->names if you need to substitute anything else.