This helps reduce the amount of import cycles we have in the compose
code path following the migration to a fancier stream input.
`compose_closed_ui.initialize()` was moved further down in the
initialization order because it relies on the dropdown widget
to be defined.
This is needed for the compose stream dropdown widget,
which is also updated here. Now when a user is subscribed
or unsubscribed from a stream, or a stream is renamed, or
or a stream is deleted, the dropdown widget updates
accordingly. This fixes a regression of this functionality
that happened during the switch to the dropdown.
This lets us simplify the long-ish ‘../../static/js’ paths, and will
remove the need for the ‘zrequire’ wrapper.
Signed-off-by: Anders Kaseorg <anders@zulip.com>