Add notebook executor as service function and add codeact agent.

[garyzhang99]

Description

• Example for the codeact agent use the notebook executor interactively. Reference https://github.com/xingyaoww/code-act for more information.
• Service function can be use with states inside a class. e.g.

from agentscope.service.service_toolkit import *
from agentscope.service.service_status import ServiceExecStatus
from agentscope.service.service_response import ServiceResponse

class Counter:
    def __init__(self, c=0):
        self.c = c
    def add_counter(self, a: int):
        """
        The counter for agent to use. Add `a` to the count value.
        Args:
            a (`int`):
                The number to add to count value.
        Returns:
            count_value += a
        """
        self.c += a
        return ServiceResponse(ServiceExecStatus.SUCCESS, self.c)

counter = Counter(0)
service_toolkit = ServiceToolkit()
service_toolkit.add(counter.add_counter)
print(service_toolkit.tools_instruction)
input_obs = [{"name": "add_counter", "arguments":{"a": 1}}]
res_of_string_input = service_toolkit.parse_and_call_func(input_obs)
print(res_of_string_input)

Checklist

Please check the following items before code is ready to be reviewed.

• Code has passed all tests
• Docstrings have been added/updated in Google Style
• Documentation has been updated
• Code is ready for review

[DavdGao]

I haven't finished the review, but leave some comments in this PR. Please try to solve them first.

Besides, before we find a better way to handle the stateful service functions. Please move this service class into example rather than in the library.