support skip unsupported language in code executor

[yidasanqian]

I hope the code executor can skip unsupported code blocks.

When the model generates an ECharts code block in Markdown format (```echarts), the following exception is thrown:

    |     async for message in self.group_chat.run_stream(
    |   File "d:\Develop\conda\envs\ai_table\Lib\site-packages\autogen_agentchat\teams\_group_chat\_base_group_chat.py", line 518, in run_stream
    |     raise RuntimeError(str(message.error))
    | RuntimeError: ValueError: Unsupported language: echarts
    | Traceback:
    | Traceback (most recent call last):
    |
    |   File "d:\Develop\conda\envs\ai_table\Lib\site-packages\autogen_agentchat\teams\_group_chat\_chat_agent_container.py", line 79, in handle_request
    |     async for msg in self._agent.on_messages_stream(self._message_buffer, ctx.cancellation_token):
    |
    |   File "d:\Develop\conda\envs\ai_table\Lib\site-packages\autogen_agentchat\agents\_code_executor_agent.py", line 427, in on_messages_stream
    |     execution_result = await self.execute_code_block(code_blocks, cancellation_token)
    |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    |   File "d:\Develop\conda\envs\ai_table\Lib\site-packages\autogen_agentchat\agents\_code_executor_agent.py", line 576, in execute_code_block
    |     result = await self._code_executor.execute_code_blocks(code_blocks, cancellation_token=cancellation_token)
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    |   File "d:\Develop\conda\envs\ai_table\Lib\site-packages\autogen_ext\code_executors\docker\_docker_code_executor.py", line 403, in execute_code_blocks
    |     return await self._execute_code_dont_check_setup(code_blocks, cancellation_token)
    |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    |   File "d:\Develop\conda\envs\ai_table\Lib\site-packages\autogen_ext\code_executors\docker\_docker_code_executor.py", line 344, in _execute_code_dont_check_setup
    |     command = ["timeout", str(self._timeout), lang_to_cmd(lang), filename]
    |                                               ^^^^^^^^^^^^^^^^^
    |
    |   File "d:\Develop\conda\envs\ai_table\Lib\site-packages\autogen_ext\code_executors\_common.py", line 171, in lang_to_cmd
    |     raise ValueError(f"Unsupported language: {lang}")
    |
    | ValueError: Unsupported language: echarts