key_manager: Use regular std::string instead of std::string_view

The benefit of std::string_view comes from the idea of avoiding copies
(essentially acting as a non-owning view), however if we're just going
to copy into a local variable immediately, there's not much benefit
gained here.

src/core/crypto/key_manager.cpp

@@ -66,8 +66,7 @@ KeyManager::KeyManager() {
     AttemptLoadKeyFile(yuzu_keys_dir, hactool_keys_dir, "title.keys", true);
 }
 
-void KeyManager::LoadFromFile(std::string_view filename_, bool is_title_keys) {
-    const auto filename = std::string(filename_);
+void KeyManager::LoadFromFile(const std::string& filename, bool is_title_keys) {
     std::ifstream file(filename);
     if (!file.is_open())
         return;
@@ -107,11 +106,8 @@ void KeyManager::LoadFromFile(std::string_view filename_, bool is_title_keys) {
     }
 }
 
-void KeyManager::AttemptLoadKeyFile(std::string_view dir1_, std::string_view dir2_,
-                                    std::string_view filename_, bool title) {
-    const std::string dir1(dir1_);
-    const std::string dir2(dir2_);
-    const std::string filename(filename_);
+void KeyManager::AttemptLoadKeyFile(const std::string& dir1, const std::string& dir2,
+                                    const std::string& filename, bool title) {
     if (FileUtil::Exists(dir1 + DIR_SEP + filename))
         LoadFromFile(dir1 + DIR_SEP + filename, title);
     else if (FileUtil::Exists(dir2 + DIR_SEP + filename))

src/core/crypto/key_manager.h

@@ -5,6 +5,7 @@
 #pragma once
 
 #include <array>
+#include <string>
 #include <type_traits>
 #include <unordered_map>
 #include <vector>
@@ -109,9 +110,9 @@ private:
     std::unordered_map<KeyIndex<S256KeyType>, Key256> s256_keys;
 
     bool dev_mode;
-    void LoadFromFile(std::string_view filename, bool is_title_keys);
-    void AttemptLoadKeyFile(std::string_view dir1, std::string_view dir2, std::string_view filename,
-                            bool title);
+    void LoadFromFile(const std::string& filename, bool is_title_keys);
+    void AttemptLoadKeyFile(const std::string& dir1, const std::string& dir2,
+                            const std::string& filename, bool title);
 
     static const std::unordered_map<std::string, KeyIndex<S128KeyType>> s128_file_id;
     static const std::unordered_map<std::string, KeyIndex<S256KeyType>> s256_file_id;