Rename "(no topic)" to "general chat"

[alya]

In zulip/zulip#23291, we plan to rename "(no topic)" to "general chat". This is expected to require some work to support on mobile, but the details of that are TBD pending design decisions that have not been finalized yet.

References

• #api design
• #design, for user/product motivation and UX choices
• Web app / server issue: Rename "(no topic)" to "general chat" zulip#23291
• zulip-flutter issue: Handle no-topic topic ("general chat") zulip-flutter#1250

[gnprice]

This feature appears to be landing in the upcoming Zulip Server 10, and will be one of the headline features there. So it'll be one of the few features we build for this legacy app.

I think the plan I'd like to pursue is to develop the feature first in zulip-flutter (zulip/zulip-flutter#1250), because development is more efficient in the Flutter app. Then when we've worked out all the questions there about what's involved and how the feature should work, we can port the changes over to this codebase.

This remains a task for the core team; we aren't able to spend time helping people work with the legacy codebase. For anyone interested in contributing to Zulip, see the zulip-flutter repo's README and Zulip's guide to contributing:
https://zulip.readthedocs.io/en/latest/contributing/contributing.html