minor: Test round-trip behavior for mutes.
minor: Test round-trip behavior for mutes.

Instead of peeking directly at the DB to verify our mutes are
set correctly, we now use the library function.  This prepares
us to modify the DB internals while preserving the tests.

showell/zulip,shubhamdhama/zulip,rht/zulip,verma-varsha/zulip,punchagan/zulip,brainwane/zulip,hackerkid/zulip,brockwhittaker/zulip,dhcrzf/zulip,dhcrzf/zulip,hackerkid/zulip,brainwane/zulip,andersk/zulip,zulip/zulip,synicalsyntax/zulip,punchagan/zulip,brainwane/zulip,showell/zulip,tommyip/zulip,mahim97/zulip,jackrzhang/zulip,jackrzhang/zulip,synicalsyntax/zulip,amanharitsh123/zulip,jackrzhang/zulip,zulip/zulip,amanharitsh123/zulip,zulip/zulip,brainwane/zulip,timabbott/zulip,timabbott/zulip,kou/zulip,dhcrzf/zulip,Galexrt/zulip,brockwhittaker/zulip,shubhamdhama/zulip,shubhamdhama/zulip,rht/zulip,synicalsyntax/zulip,shubhamdhama/zulip,dhcrzf/zulip,mahim97/zulip,eeshangarg/zulip,showell/zulip,tommyip/zulip,tommyip/zulip,kou/zulip,rht/zulip,brainwane/zulip,zulip/zulip,rht/zulip,andersk/zulip,showell/zulip,brockwhittaker/zulip,verma-varsha/zulip,tommyip/zulip,timabbott/zulip,andersk/zulip,dhcrzf/zulip,amanharitsh123/zulip,Galexrt/zulip,kou/zulip,tommyip/zulip,jackrzhang/zulip,punchagan/zulip,andersk/zulip,verma-varsha/zulip,amanharitsh123/zulip,andersk/zulip,showell/zulip,verma-varsha/zulip,brockwhittaker/zulip,eeshangarg/zulip,kou/zulip,mahim97/zulip,hackerkid/zulip,tommyip/zulip,jackrzhang/zulip,kou/zulip,synicalsyntax/zulip,amanharitsh123/zulip,punchagan/zulip,zulip/zulip,Galexrt/zulip,hackerkid/zulip,rishig/zulip,shubhamdhama/zulip,Galexrt/zulip,verma-varsha/zulip,dhcrzf/zulip,eeshangarg/zulip,brockwhittaker/zulip,shubhamdhama/zulip,kou/zulip,Galexrt/zulip,synicalsyntax/zulip,brainwane/zulip,timabbott/zulip,punchagan/zulip,timabbott/zulip,jackrzhang/zulip,verma-varsha/zulip,brainwane/zulip,punchagan/zulip,synicalsyntax/zulip,rishig/zulip,brockwhittaker/zulip,hackerkid/zulip,rishig/zulip,mahim97/zulip,rht/zulip,kou/zulip,andersk/zulip,mahim97/zulip,rishig/zulip,rht/zulip,rishig/zulip,zulip/zulip,timabbott/zulip,eeshangarg/zulip,Galexrt/zulip,mahim97/zulip,eeshangarg/zulip,showell/zulip,shubhamdhama/zulip,rht/zulip,rishig/zulip,eeshangarg/zulip,showell/zulip,hackerkid/zulip,hackerkid/zulip,dhcrzf/zulip,eeshangarg/zulip,amanharitsh123/zulip,zulip/zulip,rishig/zulip,jackrzhang/zulip,andersk/zulip,timabbott/zulip,tommyip/zulip,Galexrt/zulip,punchagan/zulip,synicalsyntax/zulip