Feature request: lint for dropped exception after `.add_note()`

[Zac-HD]

try:
    something()
except Exception as e:
    e.add_note("some helpful context")

This code is easy to write, but it has a nasty problem: you've just suppressed the exception! I think there should be a lint warning which triggers if you .add_note() an exception which is not either followed by a raise or raise e, or included in a function call or rhs of an assignment expression.

[cooperlees]

Sounds sane and I welcome the PR.