C++17ification.

C++17ification!

- Filesystem interaction now uses std::filesystem::path.
- Usage of const char*, std::string have been changed to
  std::string_view where appropriate.
- Usage of printf-style functions changed to use fmt.

src/xenia/base/premake5.lua

@@ -5,6 +5,9 @@ project("xenia-base")
   uuid("aeadaf22-2b20-4941-b05f-a802d5679c11")
   kind("StaticLib")
   language("C++")
+  links({
+    "fmt"
+  })
   defines({
   })
   local_platform_files()