Enhance message data handling and editor functionality

- Updated ReadAllTextData to return a vector of MessageData instead of modifying an external list, improving data management.
- Added support for special elements in ParseMessageData to enhance message parsing capabilities.
- Introduced DisplayTextOverflowError function for better error handling in message saving.
- Refactored MessageEditor to utilize the new ReadAllTextData signature and improved expanded message handling.
- Cleaned up unused functions and variables in MessageEditor for better code organization.

src/app/editor/message/message_data.h

@@ -310,7 +310,7 @@ constexpr int kTextData2 = 0x75F40;
 constexpr int kTextData2End = 0x773FF;
 
 // Reads all text data from the ROM and returns a vector of MessageData objects.
-void ReadAllTextData(Rom *rom, std::vector<MessageData> &list_of_texts_);
+std::vector<MessageData> ReadAllTextData(uint8_t *rom, int pos = kTextData);
 
 }  // namespace editor
 }  // namespace yaze