Start new conversation button's tooltip not updating in DM narrow when direct messages are disabled.

[sayamsamal]

When an organization disables direct messages, the "Start new conversation" button's tooltip no longer updates when a user navigates to the direct messages; instead it retains whatever tooltip was present on it from the previous view/narrow.

We want the tooltip to show "New direct message (x)" as expected.

Note

A user can always DM themselves or a bot, even when direct messages are disabled in an org — the reason why we don't disable the "Start new conversation" button. (#28412)

CZO discussion

Steps to reproduces:
Considering direct messages are disabled for the org (Settings > Organization permissions > Other permissions)

1. Go to a stream, #design for example and hover over the "Start new conversation" button — it shows "New topic (c)"
2. Go to direct message, hover of the "Start new conversation" button — it still shows "New topic (c)", whereas we expect it to show "New direct message (x)"

[kennethnrk]

@sayamsamal I've opened a PR for this issue. Please review it when you get the chance.