Render exception notes in tracebacks

[dlukes]

In Python 3.11, exceptions have gained the ability to have notes added to them via an add_note method. Standard tracebacks render these as additional lines under the main error message:

try:
    raise KeyError("key")
except Exception as e:
    e.add_note("Unexpected error while calling LLM.")
    raise e

Traceback (most recent call last):
  File "/Users/david/repos/eva/insights/e.py", line 15, in <module>
    raise e
  File "/Users/david/repos/eva/insights/e.py", line 12, in <module>
    raise KeyError("key")
KeyError: 'key'
Unexpected error while calling LLM.

Rich tracebacks currently omit these:

# /// script
# requires-python = ">=3.11"
# dependencies = [
#     "rich",
# ]
# ///
from rich.traceback import install
install()
try:
    raise KeyError("key")
except Exception as e:
    e.add_note("Unexpected error while calling LLM.")
    raise e

But they should probably include them? Notes might contain relevant info that's useful for debugging the issue that caused the exception.

Not sure what the aesthetics should be, here's some prior art from rustc to get ideas going (see lines with = note:):