message: Extract `ShellOpenCommand` to `constexpr` value
  Note that `std::string` is not currently allowed for `constexpr` values,
  so we need to use either a raw `const char*` or a `std::string_view`.
diff: #include "ShellOpenPath.h"
  +#include <string_view>
  #include <cstdlib>
  -void shellOpenPath(const std::string& path)
  +namespace
  {
  #if defined(_WIN32)
  - system(("start " + path).c_str());
  + constexpr const std::string_view ShellOpenCommand{"start"};
  #elif defined(__APPLE__)
  - system(("open " + path).c_str());
  + constexpr const std::string_view ShellOpenCommand{"open"};
  #elif defined(__linux__)
  - system(("xdg-open " + path).c_str());
  + constexpr const std::string_view ShellOpenCommand{"xdg-open"};
  #else
  - #pragma message("Open folder on the current platform not implemented.")
  + #pragma message("Constant `ShellOpenCommand` not defined for the current platform.")
  #endif
  }
  +
  +
  +void shellOpenPath(const std::string& path)
  +{
  + system((std::string{ShellOpenCommand} + " " + path).c_str());
  +}
  