Made some changes from review comments:

- Made LoadKernelSystemMode return a pair consisting of a system mode and a result code (Could use review).
- Deleted ErrorOpenGL error code in favor of just having ErrorVideoCore.
- Made dialog messages more clear.
- Compared archive ID in fs_user.cpp to ArchiveIdCode::NCCH as opposed to hex magic.
- Cleaned up some other stuff.

src/core/hle/service/fs/archive.cpp

@@ -257,11 +257,9 @@ ResultVal<ArchiveHandle> OpenArchive(ArchiveIdCode id_code, FileSys::Path& archi
     LOG_TRACE(Service_FS, "Opening archive with id code 0x%08X", id_code);
 
     auto itr = id_code_map.find(id_code);
-    if (itr == id_code_map.end()) {
-        // TODO: Verify error against hardware
-        return ResultCode(ErrorDescription::NotFound, ErrorModule::FS, ErrorSummary::NotFound,
-                          ErrorLevel::Permanent);
-    }
+    if (itr == id_code_map.end())
+        return ResultCode(ErrorDescription::FS_NotFound, ErrorModule::FS, ErrorSummary::NotFound,
+                          ErrorLevel::Status);
 
     CASCADE_RESULT(std::unique_ptr<ArchiveBackend> res, itr->second->Open(archive_path));