Black 23 enforces some slightly more specific rules about empty line
counts and redundant parenthesis removal, but the result is still
compatible with Black 22.
(This does not actually upgrade our Python environment to Black 23
yet.)
Signed-off-by: Anders Kaseorg <anders@zulip.com>
Previously, alert words were a JSON list of strings stored in a
TextField on user_profile. That hacky model reflected the fact that
they were an early prototype feature.
This commit migrates from that to a separate table, 'AlertWord'. The
new AlertWord has user_profile, word, id and realm(denormalization so
we can provide a nice index for fetching all the alert words in a
realm).
This transition requires moving the logic for flushing the Alert Words
caches to their own independent feature.
Note that this commit should not be cherry-picked without the
following commit, which fixes case-sensitivity issues with Alert Words.