Allow builtin functions when "*" in authorized imports

[suryabdev]

Fix for #1830

Even if the user passes "*" in the authorized imports (Unrestricted mode), builtin functions aren't allowed
I think it is fair for the user to assume that builtin functions will be available when they use *

Repro example

Code to reproduce the issue

from smolagents import LocalPythonExecutor
executor = LocalPythonExecutor(additional_authorized_imports=['*'])
executor.send_tools({})
print(executor("""with open('sample.txt', 'rb') as f:
    data = f.read()
print(data)"""))

Error

smolagents.local_python_executor.InterpreterError: Code execution failed at line 'with open('myfile.xlsx', 'rb') as f:
    data = f.read()' due to: InterpreterError: Forbidden function evaluation: 'open' is not among the explicitly allowed tools or defined/imported in the preceding code

After change

CodeOutput(output=None, logs="b'hello world!'\n", is_final_answer=False)

Use case from GH Issue

• User wants to make smolagents work with local files.
• They've modified the prompt to indicate that there are authorized files the LLM can access.
• They are passing additional_authorized_imports=["*"].
• But when the generated python code tries to open the file the forbidden function error is faced.
  Side note: The LLM retries with pandas.open and that passes

[suryabdev]

Interestingly, open will work while other builtin functions like exec will get caught at

smolagents/src/smolagents/local_python_executor.py

Line 859 in a4850b9

if (inspect.getmodule(func) == builtins) and inspect.isbuiltin(func) and (func not in static_tools.values()):

With

smolagents.local_python_executor.InterpreterError: Code execution failed at line 'exec(code_string)' due to: InterpreterError: Invoking a builtin function that has not been explicitly added as a tool is not allowed (exec).

Because, open belongs to the io module

>>> import inspect
>>> inspect.getmodule(open)
<module '_io' (built-in)>
>>> inspect.getmodule(exec)
<module 'builtins' (built-in)>

I'm not a python security expert. Should we allow eval/exec if the user says it is ok (By passing in *)?

[suryabdev]

cc: @albertvillanova / @aymeric-roucher Please take a look when free

[suryabdev]

The new addition allows eval etc to work when '*' is passed

[suryabdev]

Added a unit test