Improve storage initialization and error handling, refactoring

Add checks to ensure that:

- The first storage path, i.e. the path of the designated user directory, is added to the storage successfully.
- The folder of the user directory is created successfully (or already exists).
- The default folders inside the user directory are created successfully (or already exist).

On failure, the client/server will quit immediately on launch. The client will quit with an error message popup showing the log messages of the failed storage initialization. Closes ddnet#3758, which presumably was caused by the user directory not being accessible. Closes ddnet#9165.

Refactoring:

- Consistently use the `log_` functions for logging.
- Extract functions in `CStorage` to improve readability.
- Add `enum class EInitializationType` for storage initialization.

src/engine/client/client.cpp

@@ -4707,7 +4707,23 @@ int main(int argc, const char **argv)
 		delete pEngine;
 	});
 
-	IStorage *pStorage = CreateStorage(IStorage::STORAGETYPE_CLIENT, argc, argv);
+	IStorage *pStorage;
+	{
+		CMemoryLogger MemoryLogger;
+		MemoryLogger.SetParent(log_get_scope_logger());
+		{
+			CLogScope LogScope(&MemoryLogger);
+			pStorage = CreateStorage(IStorage::EInitializationType::CLIENT, argc, argv);
+		}
+		if(!pStorage)
+		{
+			log_error("client", "Failed to initialize the storage location (see details above)");
+			std::string Message = "Failed to initialize the storage location. See details below.\n\n" + MemoryLogger.ConcatenatedLines();
+			pClient->ShowMessageBox("Storage Error", Message.c_str());
+			PerformAllCleanup();
+			return -1;
+		}
+	}
 	pKernel->RegisterInterface(pStorage);
 
 	pFutureAssertionLogger->Set(CreateAssertionLogger(pStorage, GAME_NAME));

src/engine/server/main.cpp

@@ -120,7 +120,12 @@ int main(int argc, const char **argv)
 	IEngine *pEngine = CreateEngine(GAME_NAME, pFutureConsoleLogger, 2 * std::thread::hardware_concurrency() + 2);
 	pKernel->RegisterInterface(pEngine);
 
-	IStorage *pStorage = CreateStorage(IStorage::STORAGETYPE_SERVER, argc, argv);
+	IStorage *pStorage = CreateStorage(IStorage::EInitializationType::SERVER, argc, argv);
+	if(!pStorage)
+	{
+		log_error("server", "failed to initialize storage");
+		return -1;
+	}
 	pKernel->RegisterInterface(pStorage);
 
 	pFutureAssertionLogger->Set(CreateAssertionLogger(pStorage, GAME_NAME));