[libxml2] Update to latest commit, remove wrapper

[JackBoosY]

• Update to latest commit to use the internal CMakeLists.txt
• Remove vcpkg-cmake-wrapper and usage since the official already provide the cmake target

Replaced PR #14478.
Fixes #14468.

[JackBoosY]

cc @Neumann-A for review this PR.
cc @jmelas for test this PR.

[traversaro]

FYI the upstream libxml2 project now has an official CMake build system (see https://gitlab.gnome.org/GNOME/libxml2/-/blob/master/CMakeLists.txt), and even the autotools build system installs a CMake config file (see https://gitlab.gnome.org/GNOME/libxml2/-/blob/master/libxml2-config.cmake.in). I am a bit afraid that adding a third vcpkg-specific variant will complicate life of libraries maintainers that need to support all this variants.

[JackBoosY]

@traversaro That's awesome, I will try to update libxml2 to use that (but it's not included in official release).

[Neumann-A]

is there a reason not to switch to vcpkg_configure_make ? (Assuming there are problems with upstreams CMakeLists.txt)

[JackBoosY]

@Neumann-A If CMakelists.txt has no errors, we prefer to use cmake to build all ports.

[Neumann-A]

no no no..... don't do that. You are patching the hell out of downstream ports for some unnecessary reason. Fix the CMake FindLibXml2.cmake module with a vcpkg-cmake-wrapper.cmake and be done with it!

You can override all manual find_library calls by doing a find_library call yourself before the find_package() call since find_library sets a CACHE variable.

[JackBoosY]

@Neumann-A I've already realized that...
The official provided cmake is incomplete, I think we should wait for upstream fix these issues.

Will open another PR to fix the related bug.