Merge PR #716: Fix Unicode paths on Windows

Preserve native Windows paths for filesystem operations, command-line options,
and game icons. Complete Unicode handling in recursive file listings and file
logging, restore unmounting by host directory, and extend regression coverage.

Original implementation by Augusto Domingos (@AghastyGD); retain all five of
his PR commits and include the reviewed follow-up fixes.

Closes #714

Co-authored-by: Augusto Domingos <augustodomingosvasco@gmail.com>

src/common/logging/log.cpp

@@ -3,7 +3,6 @@
 
 #include "common/assert.h"
 #include "common/emulatorConfig.h"
-#include "common/stringUtils.h"
 
 #include <cstdio>
 #include <filesystem>
@@ -47,7 +46,7 @@ std::shared_ptr<spdlog::logger> MakeFileLogger(std::string                  name
 	}
 
 	auto sink =
-	    std::make_shared<spdlog::sinks::basic_file_sink_mt>(Common::PathToString(path), true);
+	    std::make_shared<spdlog::sinks::basic_file_sink_mt>(path.native(), true);
 	return MakeLogger(std::move(name), std::move(sink));
 }