message: Add 'links_for_embed' to message_dict.
message: Add 'links_for_embed' to message_dict.

There is a bug where we send event for even
those messages which do not have embedded links
as we are using single set 'links_for_embed' to
check whether we have to send event for
embedded links or not.

This commit fixes the bug by adding 'links_for_embed'
in message dict itself and send the event only
if that message has embedded links.

punchagan/zulip,eeshangarg/zulip,eeshangarg/zulip,kou/zulip,eeshangarg/zulip,kou/zulip,andersk/zulip,zulip/zulip,showell/zulip,rht/zulip,rht/zulip,hackerkid/zulip,kou/zulip,rht/zulip,andersk/zulip,zulip/zulip,zulip/zulip,kou/zulip,hackerkid/zulip,kou/zulip,punchagan/zulip,punchagan/zulip,zulip/zulip,eeshangarg/zulip,punchagan/zulip,punchagan/zulip,punchagan/zulip,hackerkid/zulip,hackerkid/zulip,rht/zulip,showell/zulip,punchagan/zulip,zulip/zulip,showell/zulip,showell/zulip,zulip/zulip,showell/zulip,hackerkid/zulip,andersk/zulip,andersk/zulip,hackerkid/zulip,kou/zulip,eeshangarg/zulip,andersk/zulip,rht/zulip,andersk/zulip,eeshangarg/zulip,andersk/zulip,hackerkid/zulip,kou/zulip,showell/zulip,eeshangarg/zulip,rht/zulip,zulip/zulip,rht/zulip,showell/zulip