<!-- If your PR fixes issues, please note that here by adding "Fixes
#NNNNNN." for each fixed issue on separate lines. -->
Fixes https://github.com/microsoft/vcpkg/issues/29496
- Remove unnecessary dependencies: `spirv-headers`.
- Add export for target `spirv-reflect-static`.
- Install headers of the port and fix usage defects.
Usage test passed with `x64-windows` triplet.
- [x] Changes comply with the [maintainer
guide](https://github.com/microsoft/vcpkg-docs/blob/main/vcpkg/contributing/maintainer-guide.md).
- [ ] ~SHA512s are updated for each updated download.~
- [ ] ~The "supports" clause reflects platforms that may be fixed by
this new version.~
- [ ] ~Any fixed [CI
baseline](https://github.com/microsoft/vcpkg/blob/master/scripts/ci.baseline.txt)
entries are removed from that file.~
- [ ] ~Any patches that are no longer applied are deleted from the
port's directory.~
- [x] The version database is fixed by rerunning `./vcpkg x-add-version
--all` and committing the result.
- [x] Only one version is added to each modified port's versions file.
