Added include-what-you-use pragmas to:
* let IWYU point users to the main include file CLI/CLI.hpp
* tell IWYU that CLI/CLI.hpp is the main exporting header.
This should fix#816
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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Philip Top <phlptp@gmail.com>