utils: Use u8path to fix possible string conversion crashes on Windows

All other path operations in the code base already use u8path to ensure
that the strings provided by libobs (which will either be ASCII or
UTF-8 byte sequences) are correctly converted into UTF-16 strings.

Author: PatTheMav

src/utils/Json.cpp

@@ -197,7 +197,7 @@ bool Utils::Json::SetJsonFileContent(std::string fileName, const json &content,
 {
 	if (makeDirs) {
 		std::error_code ec;
-		auto p = std::filesystem::path(fileName).parent_path();
+		auto p = std::filesystem::u8path(fileName).parent_path();
 		if (!ec && !std::filesystem::exists(p, ec))
 			std::filesystem::create_directories(p, ec);
 		if (ec) {