This commit changes the way compose box responds to a file drop or paste.
Currently, the compose box expands only after the file is uploaded to the
server, which can cause confusion if the upload fails and there is also no
progress bar. With the update, the compose box will expand immediately upon
drop or paste events showing the status of upload. Also it was opening
the stream compose box even if we are in a direct message, now it starts
a reply.
Fixes#24654.
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>