[spirv-tools] Add cmake targets

[cwfitzgerald]

This PR adds a patch to spirv-tools to give it cmake targets to import.

Notes:

• There was an extra shared library that was being built at the same time as the static we thought we were getting. I have disabled this for now. However, that means we could possibly reopen spirv-tools to being built as both a static and dynamic library through another patch, however that is outside the scope of this PR.
• Because of change I made above, it would be basically impossible to merge this into upstream as it would change their defaults in their build system and I would have to justify such a breaking change.

[PhoebeHui]

@cwfitzgerald, thanks for contributing to vcpkg! All triplets build successfully.

[grdowns]

Good catch. Thanks for the PR, @cwfitzgerald!