node tests: Use stream message in message_events.
node tests: Use stream message in message_events.

We use a somewhat more realistic message, mostly
to prep for testing some mention/unread stuff in
a subsequent commit.

We also set message booleans.

Unfortunately, `recent_senders` is kind of awkward
for checking a single message, since its only
public API is for sorting.  I don't bother with it.

But I do check the `topic_data` interaction.

rht/zulip,andersk/zulip,synicalsyntax/zulip,showell/zulip,synicalsyntax/zulip,showell/zulip,punchagan/zulip,timabbott/zulip,zulip/zulip,showell/zulip,hackerkid/zulip,punchagan/zulip,shubhamdhama/zulip,brainwane/zulip,brainwane/zulip,timabbott/zulip,zulip/zulip,timabbott/zulip,kou/zulip,zulip/zulip,shubhamdhama/zulip,brainwane/zulip,brainwane/zulip,rht/zulip,showell/zulip,punchagan/zulip,zulip/zulip,andersk/zulip,punchagan/zulip,hackerkid/zulip,zulip/zulip,kou/zulip,shubhamdhama/zulip,eeshangarg/zulip,shubhamdhama/zulip,kou/zulip,shubhamdhama/zulip,eeshangarg/zulip,zulip/zulip,andersk/zulip,punchagan/zulip,synicalsyntax/zulip,kou/zulip,rht/zulip,andersk/zulip,punchagan/zulip,kou/zulip,timabbott/zulip,showell/zulip,timabbott/zulip,eeshangarg/zulip,hackerkid/zulip,eeshangarg/zulip,shubhamdhama/zulip,brainwane/zulip,synicalsyntax/zulip,hackerkid/zulip,showell/zulip,synicalsyntax/zulip,hackerkid/zulip,andersk/zulip,rht/zulip,kou/zulip,punchagan/zulip,synicalsyntax/zulip,rht/zulip,brainwane/zulip,zulip/zulip,rht/zulip,andersk/zulip,andersk/zulip,timabbott/zulip,eeshangarg/zulip,synicalsyntax/zulip,showell/zulip,eeshangarg/zulip,brainwane/zulip,timabbott/zulip,kou/zulip,hackerkid/zulip,hackerkid/zulip,eeshangarg/zulip,rht/zulip,shubhamdhama/zulip