Add manifold port

[JeffreyWardman]

• 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.

[JeffreyWardman]

@microsoft-github-policy-service agree

[JeffreyWardman]

I was able to build locally. manifold builds files into lib/cmake which raises warnings, which seem to have caused the CI/CD to fail. Once adding the ignore warnings, I get the current errors only in CI/CD.

Initial error due to warnings: https://dev.azure.com/vcpkg/public/_build/results?buildId=109648&view=logs&j=878666d5-db33-5b27-9e7d-b0c7ee352005&t=69176ca8-c93b-5311-0f74-6cb12a2b3f92&l=8209

After adding the ignore fixes: https://dev.azure.com/vcpkg/public/_build/results?buildId=109649&view=logs&j=878666d5-db33-5b27-9e7d-b0c7ee352005&t=69176ca8-c93b-5311-0f74-6cb12a2b3f92&l=8184

This is my first commit to vcpkg. It'd be great if I can get advice on how to handle these kinds of warnings for it to be merged.