unread: Fix messages that cannot be marked as read in narrows.
unread: Fix messages that cannot be marked as read in narrows.

If you visit a narrow that has unread messages on it that aren't part
of the home view (e.g. in a muted stream), then we were never calling
`message_util.do_unread_count_updates`, and more importantly,
`unread.process_loaded_messages` on those messages.  As a result, they
would be unread, and moving the cursor over them would never mark
those messages as read (which was visible through the little green
marker never disappearing).

I can't tell whether this fixes #8042 and/or #8236; neither of them
exactly fits the description of this issue unless the PM threads in
question were muted or something, but this does feel related.

dhcrzf/zulip,hackerkid/zulip,tommyip/zulip,jackrzhang/zulip,rht/zulip,eeshangarg/zulip,tommyip/zulip,dhcrzf/zulip,eeshangarg/zulip,rishig/zulip,eeshangarg/zulip,shubhamdhama/zulip,kou/zulip,brainwane/zulip,shubhamdhama/zulip,rht/zulip,brainwane/zulip,punchagan/zulip,punchagan/zulip,rishig/zulip,shubhamdhama/zulip,dhcrzf/zulip,timabbott/zulip,hackerkid/zulip,zulip/zulip,eeshangarg/zulip,punchagan/zulip,rishig/zulip,jackrzhang/zulip,synicalsyntax/zulip,hackerkid/zulip,zulip/zulip,shubhamdhama/zulip,tommyip/zulip,hackerkid/zulip,synicalsyntax/zulip,dhcrzf/zulip,punchagan/zulip,rht/zulip,shubhamdhama/zulip,punchagan/zulip,kou/zulip,showell/zulip,eeshangarg/zulip,andersk/zulip,synicalsyntax/zulip,synicalsyntax/zulip,rishig/zulip,jackrzhang/zulip,timabbott/zulip,eeshangarg/zulip,showell/zulip,synicalsyntax/zulip,brainwane/zulip,kou/zulip,showell/zulip,andersk/zulip,timabbott/zulip,synicalsyntax/zulip,jackrzhang/zulip,synicalsyntax/zulip,tommyip/zulip,andersk/zulip,rht/zulip,kou/zulip,tommyip/zulip,rishig/zulip,rishig/zulip,jackrzhang/zulip,rishig/zulip,timabbott/zulip,shubhamdhama/zulip,showell/zulip,showell/zulip,brainwane/zulip,andersk/zulip,punchagan/zulip,zulip/zulip,tommyip/zulip,andersk/zulip,dhcrzf/zulip,andersk/zulip,showell/zulip,hackerkid/zulip,dhcrzf/zulip,kou/zulip,jackrzhang/zulip,eeshangarg/zulip,dhcrzf/zulip,andersk/zulip,kou/zulip,timabbott/zulip,rht/zulip,showell/zulip,timabbott/zulip,zulip/zulip,hackerkid/zulip,kou/zulip,rht/zulip,punchagan/zulip,rht/zulip,jackrzhang/zulip,timabbott/zulip,hackerkid/zulip,zulip/zulip,brainwane/zulip,zulip/zulip,shubhamdhama/zulip,brainwane/zulip,brainwane/zulip,zulip/zulip,tommyip/zulip