Demote inactive channels in channel-list screen

[gnprice]

The page listing the channels you're subscribed to (SubscriptionListPage) corresponds to the web app's left sidebar. Like the web left sidebar, it puts pinned channels before non-pinned channels. Unlike the web left sidebar, it doesn't currently have a concept of "inactive" channels. The sections in the list are currently Pinned, Unpinned. They should become Pinned, Active, Inactive.

Implementation details

• A user setting demote_inactive_streams controls whether to do this: https://zulip.com/help/manage-inactive-channels , and search in https://zulip.com/api/register-queue .

• Starting with feature level 323 in Zulip Server 10, stream/channel objects have a field is_inactive_stream which we should use.

  For older servers without that field, we can just skip this feature. By design the mobile app doesn't eagerly download the large volumes of messages that the web app does, which are how the web app has made a reasonable approximation of this feature for all these years before this field was added.

Related issues

• Issue in the legacy app covering this and some other changes: Group streams into sections zulip-mobile#5425