Support BUILD_SHARED_LIBS set to ON on Windows/MSVC

[traversaro]

Is your feature request related to a problem? Please describe.
Given its huge size, for some applications it is convenient to be able to compiled dart as a shared library on Windows/MSVC, to permit to share it among multiple executable.

Additional context
Discussion on this was ongoing on #1005, but that issue was closed as its main objective was reached without the need to make sure that DART supported being compiled as a shared library on Windows.

[jslee02]

Do you know what's preventing us from building DART as shared libraries? Doesn't BUILD_SHARED_LIBS work as it is?

[traversaro]

To be honest I did not tried myself, but from #1005 it seems that the situation is the following:

• The CMake variable CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS does not work as the library has more then 65k symbols, see Submit DART port to vcpkg #1005 (comment) .
• An attempt was made in C++ visibility support #1040 to add explicit visibility macros, but i guess there were some problem/doubts on where to add visibility macros for heavily templated class, and then eventually the PR was not completed.

[jslee02]

Fixed by d78c328

[traversaro]

Great, thanks a lot!

[jslee02]

Thanks for being patient with this. I had to implement some workarounds and make adjustments to the code to get it working. I will be addressing these issues and making improvements in future commits.