DiscIO/DirectoryBlob: Add ContentSource that stores data locally in std::vector.

Source/Core/DiscIO/DirectoryBlob.cpp

@@ -134,6 +134,12 @@ bool DiscContent::Read(u64* offset, u64* length, u8** buffer) const
       const ContentFixedByte& source = std::get<ContentFixedByte>(m_content_source);
       std::fill_n(*buffer, bytes_to_read, source.m_byte);
     }
+    else if (std::holds_alternative<ContentByteVector>(m_content_source))
+    {
+      const ContentByteVector& source = std::get<ContentByteVector>(m_content_source);
+      std::copy(source.m_bytes.begin() + offset_in_content,
+                source.m_bytes.begin() + offset_in_content + bytes_to_read, *buffer);
+    }
     else
     {
       PanicAlertFmt("DirectoryBlob: Invalid content source in DiscContent.");

Source/Core/DiscIO/DirectoryBlob.h

@@ -80,11 +80,18 @@ struct ContentFixedByte
   u8 m_byte;
 };
 
+// Content chunk representing an arbitrary byte sequence that's stored within the struct itself.
+struct ContentByteVector
+{
+  std::vector<u8> m_bytes;
+};
+
 using ContentSource = std::variant<ContentFile,       // File
                                    const u8*,         // Memory
                                    ContentPartition,  // Partition
                                    ContentVolume,     // Volume
-                                   ContentFixedByte   // Fixed value padding
+                                   ContentFixedByte,  // Fixed value padding
+                                   ContentByteVector  // Byte sequence
                                    >;
 
 struct BuilderContentSource