Add casbin-cpp to vcpkg

[shishirong]

Description

I issued in vcpkg,but closed by someone.
Have a expert to reopen or Pull requests about casbin-cpp.

[casbin-bot]

@EmperorYP7 @sheny1xuan @cs1137195420

[PokIsemaine]

I try again microsoft/vcpkg#28976

[nomeguy]

see: microsoft/vcpkg#29027

[PokIsemaine]

The issue was closed again, it looks like the way casbin-cpp is installed by CMake is causing some difficulty adding to vcpkg. Can anyone fix this problem and open this issue again?

[BillyONeal]

To clarify, we didn't identify a specific problem with what casbin-cpp does; only that the generated instructions did not appear to match the user instructions in https://github.com/casbin/casbin-cpp which meant that the supplied portfile.cmake didn't install the right bits for users to use.

The author of that PR, @ex-purple said:

I figured out what's wrong Library and CMake configuration are installed in the CMake User Package Registry.

I don't know what "CMake User Package Registry" means; it certainly isn't a thing understood by vcpkg. The port just needs to install the right configs or similar to ${CURRENT_PACKAGES_DIR}/share/${PORT} so that find_package works for downstream customers.

[ex-purple]

Look here
System installation (install command) is present only for headers. Library and cmake configuration are exported to the CMake User Package Registry.

CMake User Package Registry it is user specific installation. vcpkg works with system installation, so we have only headers for the vcpkg port

[PokIsemaine]

@ex-purple Thanks for your help, I would like to see if casbin-cpp needs to be changed to make it successfully added to vcpkg. If necessary, you can consider submitting a PR to casbin-cpp, which is grateful.