Feature Request: Add Support for Opcode 0x1 (Text Frame)

[skibitsky]

Hello,

Currently the SimpleWebTransport only supports WebSocket communication using opcode 0x2 (Binary Frame). This limits its use for applications that need to handle text data, like JSON or other UTF-8 encoded messages, which are transmitted using opcode 0x1 (Text Frame).

It would be great to have support for text frames as well, as this would make the library much more versatile and useful for a broader range of WebSocket applications :)