[magnum-plugins] Update head features and bundled dependency

[pezcode]

This PR updates magnum-plugins with new features available when compiling with --head, along with an update to a bundled dependency required to compile.

Note: the spirvtoolsshaderconverter feature is currently broken due to #18612

• Which triplets are supported/not supported? Have you updated the CI baseline?

  There shouldn't be any changes compared to the current port version

• Does your PR follow the maintainer guide?

  To the best of my knowledge, yes 👀

• If you have added/updated a port: Have you run ./vcpkg x-add-version --all and committed the result?

  Yessss

[ghost]

All CLA requirements met.

[github-actions]

You have modified or added at least one portfile where deprecated functions are used.

If you feel able to do so, please consider migrating them to the new functions:
vcpkg_install_cmake -> vcpkg_cmake_install (from port vcpkg-cmake)
vcpkg_build_cmake -> vcpkg_cmake_build (from port vcpkg-cmake)
vcpkg_configure_cmake -> vcpkg_cmake_configure (Please remove the option PREFER_NINJA) (from port vcpkg-cmake)
vcpkg_fixup_cmake_targets -> vcpkg_cmake_config_fixup (from port vcpkg-cmake-config)

In the ports that use the new function, you have to add the corresponding dependencies:

{
  "name": "vcpkg-cmake",
  "host": true
},
{
  "name": "vcpkg-cmake-config",
  "host": true
}

The following files are affected:

• ports/magnum-plugins/portfile.cmake

[pezcode]

Turned into a draft PR temporarily to coordinate with @mosra. If @NancyLi1013 confirms that head-only feature dependencies are acceptable, the bundled zstd handling can be removed upstream.

[NancyLi1013]

Have you tested this features? @pezcode

[pezcode]

Have you tested this features? @pezcode

I tested all the new and updated features with x64-windows and x64-windows-static.

[NancyLi1013]

LGTM now, thanks for your PR @pezcode.

[vicroms]

This port should be updated to the latest commit instead. It removes the necessity for the extra logic around --head which was never intended to be used this way.

[Squareys]

@vicroms I'm not sure if I understand: the latest commit means --head, does it not? As in that's what differentiates it from the latest release.
Of course, ideally, magnum will eventually release a new version, which will eliminate the extra logic, but until then, we shouldn't be updating the port to a HEAD version if users expect to install the latest stable release...

[vicroms]

Discussed with the rest of the team, this is fine since it acts like a no-op when a user requests unsupported features and doesn't add new dependencies for non-head users.