[libfork] new port

[ConorWilliams]

This PR adds libfork, a portable continuation stealing framework. I am the author of the package.

• Changes comply with the maintainer guide.
• The name of the port matches an existing name for this component on https://repology.org/ if possible, and/or is strongly associated with that component on search engines.
• Optional dependencies are resolved in exactly one way. For example, if the component is built with CMake, all find_package calls are REQUIRED, are satisfied by vcpkg.json's declared dependencies, or disabled with CMAKE_DISABLE_FIND_PACKAGE_Xxx.
• The versioning scheme in vcpkg.json matches what upstream says.
• The license declaration in vcpkg.json matches what upstream says.
• The installed as the "copyright" file matches what upstream says.
• The source code of the component installed comes from an authoritative source.
• The generated "usage text" is accurate. See adding-usage for context.
• The version database is fixed by rerunning ./vcpkg x-add-version --all and committing the result.
• Only one version is in the new port's versions file.
• Only one version is added to each modified port's versions file.

[ConorWilliams]

@microsoft-github-policy-service agree

[jimwang118]

Note: I will be converting your PR to draft status. The above suggested changes are only recommendations. If you are willing to adopt them, please click "ready for review" after making the modifications. If you do not wish to make any changes, please click "ready for review" directly. That way, I can be aware that you've responded since you can't modify the tags.

[jimwang118]

May I ask where the compiled lib file is installed?

[ConorWilliams]

May I ask where the compiled lib file is installed?

It is a header-only lib

[jimwang118]

Usage test pass with following triplets:

x86-windows
x64-windows
x64-windows-static

[ConorWilliams]

Usage test pass with following triplets:

x86-windows
x64-windows
x64-windows-static

Fantastic, are we good to merge?