Change in how muted_topics tuples are represented

[timabbott]

We added an additional field, date_muted, at the end of muted_topics tuples, in
zulip/zulip@9340cd1 as part of zulip/zulip#13833.

Opening an issue here. Ultimately, we don't use tuples anywhere else for a reason, and may want to change the interface further, but this should at least be backwards-compatible.

See zulip/zulip#13833 (comment) for testing that it doesn't break the existing mobile app to have made this change.

[gnprice]

Thanks!

I think the steps I'd like us to take for this right now are:

• We have a type MuteTuple that describes these. It should be extended to cover both the old and new version of this API.
  • It should also get a comment pointing at relevant API documentation if any, or else at this issue, and saying at what server version the API changed.
• We bring those objects verbatim into our Redux state. That's fine for now but we should clean up a couple of the consequences:

  • Search for getMute to see where it's used. Some of those places search through the list of tuples directly. Instead, all of them should use the helper isTopicMuted, which does that search.

    (That way the details of the data structure matter only to that helper, and to the reducer that maintains it. In particular that will help if there's a future bigger change to the API.)