Check for reuse of binding numbers.

From the latest 4.5 specification:

> It is a compile-time or link-time error to use the same binding number for more than one image or more
than one sampler. It is a compile-time or link-time error to use the same binding number for more than one atomic counter, unless the offset for the atomic counters sharing the same binding are all different.

This still needs to be implemented.

Start by reading the quoted GLSL 4.5 specification rule and locating the compiler validation responsible for resource binding numbers. Check how images, samplers, and atomic counters are represented and validated, then add coverage for duplicate bindings and confirm the specified exceptions are enforced.

Written by the indexing model from the issue text.