Correct CMake issues

[doodspav]

• install properly without forcing us upon our consumers' consumers
• remove unnecessary options (such as platform specific ones, or ones that have no impact on building/installing)
• support alias targets helping consumers catch errors sooner
• make CMake files more structured and readable
• change minimum required version from 3.8 .. 3.23 to just 3.14
• all symbols are now private (you should probably address this asap)
• more stuff properly, i don't remember

[jeremy-rifkin]

Thank you for the PR! I will review as soon as I can.

[doodspav]

Follow up things you should probably do:

• check your flags; i removed a whole bunch because they don't affect the build (they're compiler warnings) and they belong in presets, not in the CML file
• check your macro definitions; i removed some that set some macros that didn't affect build/install (they should stay removed, but you might want to update your docs concerning that)
• fix the CMake for your tests, and maybe use a proper test framework
• fix the CMake for your dependencies (like cpptrace) which gets installed along with libassert even when being linked as a private dependency
• you now have a new header file, <assert/assert_export.hpp> that gets generated by CMake; you can include this without needing a relative include path, and you should mark all the symbols you want to be exported with ASSERT_EXPORT because right now all symbols are private (even on linux)
• update documentation to specify that people should link against assert::assert instead of assert (which no longer exists)

[doodspav]

Bear in mind that cpptrace's CMake breaks consuming an installed version of libassert consumed via find_package

[jeremy-rifkin]

Thank you again for this PR, I have integrated much of your recommendations for structure and functionality of the CMake into cpptrace on the dev branch and things seem to work well there. I will give this PR a more thorough review this weekend.

Running the CI now, some test failures are expected. No worries that there are some.