Add test to make sure all public headers are installed #17
Description
The test include_public_headers checks if all public headers are truly public. It fails if any public header has a MIMIC_CORE_PRIVATE symbol.
However the situation where there is a public header that is not installed is not covered. It would be nice to have a test for that. Because tests are run before the installation, maybe it is difficult to test that here.
Related to: #16