topic list: Skip muted topics when not zoomed.
topic list: Skip muted topics when not zoomed.

I think this probably matches users' expected behavior that muted
streams shouldn't get in their way unless the user is actively looking
for them.  If a user has a lot of muted topics with active traffic
(e.g. because topics corresponding to channels in a mirrored Slack
instance), they would previously find their 5 slots cluttered with
those muted topics even if there were unmuted topics with unread
messages.

Fixes #13677.

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