SPIRV-Tools does not provide version information in cmake support files

Searching for a package that provides cmake support files is done with find_package(), which provides the ability to limit the search to a specific minimum or exact version (see for example https://github.com/KhronosGroup/SPIRV-Headers/issues/104). To enable this, the creation and installation of an appropriate version information file `ConfigVersion.cmake` is required, which is missing in this project.

This problem was discovered at https://github.com/vsg-dev/VulkanSceneGraph/pull/514#issuecomment-1245668503.

Start by locating the CMake support files and the code that creates and installs the package configuration. Add the missing ConfigVersion.cmake generation and installation so find_package() can enforce minimum or exact versions, then verify the installed package configuration supports version-constrained lookup.

Written by the indexing model from the issue text.