core[patch]: Support injected tool args that are arbitrary types (#27045)

This adds support for inject tool args that are arbitrary types when
used with pydantic 2.

We'll need to add similar logic on the v1 path, and potentially mirror
the config from the original model when we're doing the subset.

libs/core/tests/unit_tests/test_tools.py

@@ -2090,3 +2090,18 @@ def test_structured_tool_direct_init() -> None:
 
     with pytest.raises(NotImplementedError):
         assert tool.invoke("hello") == "hello"
+
+
+def test_injected_arg_with_complex_type() -> None:
+    """Test that an injected tool arg can be a complex type."""
+
+    class Foo:
+        def __init__(self) -> None:
+            self.value = "bar"
+
+    @tool
+    def injected_tool(x: int, foo: Annotated[Foo, InjectedToolArg]) -> str:
+        """Tool that has an injected tool arg."""
+        return foo.value
+
+    assert injected_tool.invoke({"x": 5, "foo": Foo()}) == "bar"  # type: ignore