[caf] Add usage and vcpkg-cmake-wrapper

[NancyLi1013]

Describe the pull request

• What does your PR fix? Fixes install FindCAF.cmake file to where it is found by cmake  #14279

  Copy FindCAF.cmake to share/caf

  Add vcpg-cmake-wrapper.cmake

  Add usage

Note: No feature needs to test.

[BillyONeal]

I believe vcpkg_cmake_wrapper is only supposed to be used to override a built in cmake module but cmake has no such findcaf module. I'm not positive though so going to tag this requires:discussion.

[BillyONeal]

@vicroms indicates that this vcpkg_cmake_wrapper is needed for something related to cmake modules Bill doesn't understand :)

@strega-nil says that this is probably fine for now but that we should not be using vcpkg_cmake_wrapper to accomplish this task in the future.

I hope @strega-nil knows how to process this when she's "on rotation" next week 😂

[NancyLi1013]

@BillyONeal
Thanks for your further review and investigation about this.

I noticed that there are also other ports that use the similar way to handle this kind of issue. Such as stb.

So I assumed that this can be applied to other ports too.

Just mention, for caf, upstream has supported config.cmake and targets.cmake in current master, but not in current version in vcpkg.

So we can remove these two files when we update the port next time.