[osg] Fix debug targets for plugins in unofficial-osg

[cbrl]

This fixes the imported locations for the OSG plugin targets in unofficial-osg. Since these plugins are installed to the plugins/ folder, instead of bin/ or lib/, vcpkg_cmake_config_fixup will not add the debug folder prefix to the imported locations. This causes an error when running find_package(unofficial-osg COMPONENTS plugins).

To fix this issue, the relevant bit of vcpkg_cmake_config_fixup is copied into the portfile and modified to apply specifically to the plugin targets file. It's not exactly the cleanest method, but I don't think there's another way to do it that doesn't require manually patching paths outside of vcpkg_cmake_config_fixup.

• Changes comply with the maintainer guide
• SHA512s are updated for each updated download
• The "supports" clause reflects platforms that may be fixed by this new version
• Any fixed CI baseline entries are removed from that file.
• Any patches that are no longer applied are deleted from the port's directory.
• The version database is fixed by rerunning ./vcpkg x-add-version --all and committing the result.
• Only one version is added to each modified port's versions file.

[gwaldron]

This is causing a build failure when you only build release mode with a custom triplet containing:

set(VCPKG_BUILD_TYPE release)

The error message is:

- Building x64-windows-rel
CMake Error at ports/osg/portfile.cmake:139 (file):
  file failed to open for reading (No such file or directory):

    H:/vcpkg/packages/osg_x64-windows/share/unofficial-osg/osg-plugins-debug.cmake

[cbrl]

Ah, right I didn't think about the release-only triplets. I'll add a conditional on the existence of that file.