Updates operators used for narrow.activate and sent as narrow
parameters to the server to use channel and channels.
Part of stream to channel rename project.
This commit moves mainly two functions from `ui.js` to `message_live_update`,
`update_message_in_all_views` and `update_starred_view`. This is done in favor of
eliminating `ui.js` and also these functions are more closely related to
`message_live_update` module than to `ui` module.
We also move `show_message_failed` and `show_failed_message_success` to `echo.js`
for cleaner seperation of responsibilities.
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>
