This commit adds support for following a topic from the topic
three-dot menu in the left sidebar.
Three options, i.e., 'Mute topic', 'Unmute topic', and 'Follow topic',
are shown at the top of the menu (in the mentioned order), regardless
of whether the stream is muted or unmuted.
We can no longer set the topic's visibility_policy to INHERIT
(the default value) from this menu.
The changes are visible in the development environment only.
Fixes#25917.
Co-authored-by: Prakhar Pratyush <prakhar841301@gmail.com>
Co-authored-by: Hardik Dharmani <Ddharmani99@gmail.com>
Prakhar Pratyush