migrate from std::filesystem::path to io::path (WIP)

test/coders/vec3.cpp

@@ -4,9 +4,7 @@
 #include "io/io.hpp"
 
 TEST(VEC3, Decode) {
-    auto file = std::filesystem::u8path(
-        "res/models/block.vec3"
-    );
+    io::path file = "res/models/block.vec3";
     auto bytes = io::read_bytes_buffer(file);
-    auto model = vec3::load(file.u8string(), bytes);
+    auto model = vec3::load(file.string(), bytes);
 }