common/file_util: Make ReadFileToString and WriteStringToFile consistent

Makes the parameter ordering consistent, and also makes the filename
parameter a std::string. A std::string would be constructed anyways with
the previous code, as IOFile's only constructor with a filepath is one
taking a std::string.

We can also make WriteStringToFile's string parameter utilize a
std::string_view for the string, making use of our previous changes to
IOFile.

src/common/file_util.cpp

@@ -762,11 +762,11 @@ std::string GetNANDRegistrationDir(bool system) {
     return GetUserPath(UserPath::NANDDir) + "user/Contents/registered/";
 }
 
-std::size_t WriteStringToFile(bool text_file, const std::string& str, const char* filename) {
-    return FileUtil::IOFile(filename, text_file ? "w" : "wb").WriteBytes(str.data(), str.size());
+std::size_t WriteStringToFile(bool text_file, const std::string& filename, std::string_view str) {
+    return IOFile(filename, text_file ? "w" : "wb").WriteString(str);
 }
 
-std::size_t ReadFileToString(bool text_file, const char* filename, std::string& str) {
+std::size_t ReadFileToString(bool text_file, const std::string& filename, std::string& str) {
     IOFile file(filename, text_file ? "r" : "rb");
 
     if (!file.IsOpen())

src/common/file_util.h

@@ -146,9 +146,9 @@ const std::string& GetExeDirectory();
 std::string AppDataRoamingDirectory();
 #endif
 
-std::size_t WriteStringToFile(bool text_file, const std::string& str, const char* filename);
+std::size_t WriteStringToFile(bool text_file, const std::string& filename, std::string_view str);
 
-std::size_t ReadFileToString(bool text_file, const char* filename, std::string& str);
+std::size_t ReadFileToString(bool text_file, const std::string& filename, std::string& str);
 
 /**
  * Splits the filename into 8.3 format

src/yuzu_cmd/config.cpp

@@ -26,12 +26,12 @@ Config::Config() {
 Config::~Config() = default;
 
 bool Config::LoadINI(const std::string& default_contents, bool retry) {
-    const char* location = this->sdl2_config_loc.c_str();
+    const std::string& location = this->sdl2_config_loc;
     if (sdl2_config->ParseError() < 0) {
         if (retry) {
             LOG_WARNING(Config, "Failed to load {}. Creating file from defaults...", location);
             FileUtil::CreateFullPath(location);
-            FileUtil::WriteStringToFile(true, default_contents, location);
+            FileUtil::WriteStringToFile(true, location, default_contents);
             sdl2_config = std::make_unique<INIReader>(location); // Reopen file
 
             return LoadINI(default_contents, false);