Implement installer with support for ISO, STFS and SVOD. Also implement XEX Patcher. (#5)

UnleashedRecomp/install/virtual_file_system.h

@@ -0,0 +1,24 @@
+#pragma once
+
+#include <algorithm>
+#include <memory>
+
+struct VirtualFileSystem {
+    virtual ~VirtualFileSystem() { };
+    virtual bool load(const std::string &path, uint8_t *fileData, size_t fileDataMaxByteCount) const = 0;
+    virtual size_t getSize(const std::string &path) const = 0;
+    virtual bool exists(const std::string &path) const = 0;
+
+    // Concrete implementation shortcut.
+    bool load(const std::string &path, std::vector<uint8_t> &fileData)
+    {
+        size_t fileDataSize = getSize(path);
+        if (fileDataSize == 0)
+        {
+            return false;
+        }
+
+        fileData.resize(fileDataSize);
+        return load(path, fileData.data(), fileDataSize);
+    }
+};