Reduce dependency on pydantic._internal

[tcompa]

See #834.

We currently have these imports

from pydantic._internal import _generate_schema
from pydantic._internal import _typing_extra
from pydantic._internal._config import ConfigWrapper

I think we can at least get rid of the specific _typing_extra.add_module_globals function that changed when passing from 2.8.2 to 2.9.0 (pydantic/pydantic@8dc0ce3), and maybe we can also reduce dependency on ConfigWrapper. Whether we can also avoid depending on _generate_schema.GenerateSchema is TBD.

[tcompa]

Ref:

• Create model using a function signature pydantic/pydantic#1391
• Add FunctionModel for handling functions JoshuaLeivers/pydantic#1