feat: Add C++ binding to throw AttributeError

[Skylion007]

Description

Closes #687 . Adds a C++ binding to throw and catch AttributeError, useful for defining custom __setattr__. The other exception I was eyeing adding was NameError, but it is rare for any user to want to manually throw them, unlike with an AttributeError. Then again, we already expose bindings for ImportError, so I would advocating for eventually adding NameError was well at some point.

This does not significantly extend the API surface considering it supports the exceptions of other types. This doesn't implement any exception translation from C++ errors so it should be a very backwards compatible and lightweight change.

Suggested changelog entry:

* Add C++ Exception type to throw and catch AttributeError. Useful for defining custom ``__setattr__`` and ``__getattr__`` methods.

[henryiii]

Mostly dragging my feet because I'm expecting a new patch release, and this is technically a new feature. But we've let in features this small before in patches (hasn't checked to see how small it was), and it should be quite safe. Fine with me.