validate Vulkan rules for input/output locations, and avoiding overlap

Validate Vulkan rules for Location and Component decorations.
See https://www.khronos.org/registry/vulkan/specs/1.1/html/vkspec.html#fxvertex-attrib

Start with the Vulkan specification section on Location and Component decorations linked in the issue, then locate the existing SPIR-V validation for these decorations. Done means Vulkan rules for input/output locations and overlapping decorations are validated; the issue names no files or tests, so the relevant entry points must first be identified.

Written by the indexing model from the issue text.