[feature request]: exec()

[nschloe]

Problem description

The documentation lists

Removed features include:
[...]
● Support for evaluating Python code strings was removed.
[...]

I'd like to cast my vote for adding something like

nb:exec(code_as_string, nb::globals())

Reproducible example code

No response

[wjakob]

(Cleaned up the history a bit after the conversion)

If this feature is important to you, my recommendation would be that you create a PR with a draft implementation or a port from pybind11 to receive feedback and iterate on the code until it can become part of the project.

[wjakob]

(Quite likely, the code in pybind11 can be copied almost verbatim)

[nschloe]

#299