Fix installed directory structure on Windows

[Web-eWorks]

During the last major change to CMake I accidentally broke the install structure on Windows. This PR resolves that and should make the installation behavior on Windows systems more robust and easier to understand.

I've also included a potential fix for MSVC doing strange things with unicode character escape sequences in C string literals by explicitly specifying that we want the UTF-8 encoding of the unicode character.

CC @nozmajner @pcercuei to give this a test on Windows if able.

[pcercuei]

What I see if that you have a install() in the top CMake script, why isn't it in the cmake/InstallPioneer.cmake, below the spot where CMAKE_INSTALL_BINDIR is overriden?

[bszlrd]

@Web-eWorks
The binaries are now put in their proper place, but the data is in a pioneer directory:

I've tried this artifact: https:/pioneerspacesim/pioneer/actions/runs/7293314137

[Web-eWorks]

That should also be fixed now.

[bszlrd]

Confirmed, it works properly now.

[Web-eWorks]

What I see if that you have a install() in the top CMake script, why isn't it in the cmake/InstallPioneer.cmake, below the spot where CMAKE_INSTALL_BINDIR is overriden?

Replying after the fact, but essentially the InstallPioneer script is intended to setup installation directories at the start of the CMakeFile, but the install statements cannot be effectively used until the targets they're installing are defined. I'd welcome a PR to further reorganize and deduplicate the CMakeLists.txt file, but at this time I'm not going to make any major changes not required to restore existing functionality.