Add "library_arch" field support for Vulkan ICDs and layer manifests
Layer manifests version 1.2.1 introduced a new field called "library_arch" that is used to optionally specify the architecture of the library associated with a manifest.
The same field has also been added for Vulkan driver manifests. In this case the version was not bumped, so "library_arch" has been included in the latest version format 1.0.1.
The Vulkan-Loader documentation states that the only supported values are "32" and "64". However in the loader implementation there isn't a strict check to validate the "library_arch" value. For this reason we don't enforce the "32" and "64" values either, as an attempt to match what the Vulkan-Loader currently does.
Fixes: #103 (closed)