Support better management of names of archived streams

[alya]

In zulip/zulip#26661, we plan to rework how archived streams are handled. As part of making these changes, the mobile apps should ideally match the web app in how messages in archived streams are displayed.

API modeling:

• Start passing the new feature level 315 client capability (archived_channels) to get metadata on archived channels. Most existing functionality (lists of channels, etc.) should filter out archived channels.

Viewing messages in archived streams

• When viewing messages in an archived stream (e.g.,in search results), append " (archived)" to the end of the stream name. This should be marked for translation. (We can also consider using a different font or a pill in the header bar to indicate archived streams, but just "(archived)" should be fine to start with.)
• Topic links for archived streams should work. Currently, the server doesn't send data on archived streams to clients. See related discussion here.

Web app / server issue:

• Better management of names of archived streams zulip#26661

Flutter issue:

• Support better management of names of archived channels zulip-flutter#800

[timabbott]

I updated this description following #26661 being completed in the server project.

[gnprice]

Our current plan is we'll skip this in the legacy app, given that the server release it's scheduled for is the upcoming Zulip Server 10 and we're expecting to launch the new mobile app not long after.