drafts: Fix faulty draft_model addDraft and editDraft tests
drafts: Fix faulty draft_model addDraft and editDraft tests

The addDraft and editDraft tests were copying objects by reference
which meant the methods weren't tested properly. Due to this, a bug with
stubTimestamp was also discovered where the method wasn't getting stubbed

verma-varsha/zulip,Galexrt/zulip,andersk/zulip,andersk/zulip,vaidap/zulip,eeshangarg/zulip,jphilipsen05/zulip,dhcrzf/zulip,SmartPeople/zulip,jackrzhang/zulip,eeshangarg/zulip,synicalsyntax/zulip,dhcrzf/zulip,rishig/zulip,shubhamdhama/zulip,j831/zulip,tommyip/zulip,vaidap/zulip,punchagan/zulip,tommyip/zulip,kou/zulip,hackerkid/zulip,zulip/zulip,shubhamdhama/zulip,SmartPeople/zulip,amanharitsh123/zulip,eeshangarg/zulip,jackrzhang/zulip,jphilipsen05/zulip,brainwane/zulip,verma-varsha/zulip,vaidap/zulip,zulip/zulip,Galexrt/zulip,synicalsyntax/zulip,verma-varsha/zulip,ryanbackman/zulip,ryanbackman/zulip,SmartPeople/zulip,mahim97/zulip,jrowan/zulip,jrowan/zulip,eeshangarg/zulip,vabs22/zulip,tommyip/zulip,j831/zulip,hackerkid/zulip,showell/zulip,rishig/zulip,SmartPeople/zulip,jrowan/zulip,tommyip/zulip,punchagan/zulip,brainwane/zulip,timabbott/zulip,showell/zulip,timabbott/zulip,punchagan/zulip,mahim97/zulip,vaidap/zulip,vabs22/zulip,kou/zulip,zulip/zulip,hackerkid/zulip,dhcrzf/zulip,rht/zulip,showell/zulip,SmartPeople/zulip,jackrzhang/zulip,rishig/zulip,eeshangarg/zulip,vabs22/zulip,rht/zulip,amanharitsh123/zulip,brockwhittaker/zulip,synicalsyntax/zulip,showell/zulip,showell/zulip,zulip/zulip,mahim97/zulip,rishig/zulip,synicalsyntax/zulip,mahim97/zulip,jackrzhang/zulip,showell/zulip,kou/zulip,jphilipsen05/zulip,rht/zulip,vabs22/zulip,shubhamdhama/zulip,synicalsyntax/zulip,dhcrzf/zulip,timabbott/zulip,shubhamdhama/zulip,j831/zulip,Galexrt/zulip,rishig/zulip,jrowan/zulip,brainwane/zulip,jphilipsen05/zulip,showell/zulip,jphilipsen05/zulip,kou/zulip,dhcrzf/zulip,ryanbackman/zulip,punchagan/zulip,zulip/zulip,brockwhittaker/zulip,brainwane/zulip,amanharitsh123/zulip,jackrzhang/zulip,ryanbackman/zulip,eeshangarg/zulip,brainwane/zulip,jackrzhang/zulip,hackerkid/zulip,jackrzhang/zulip,ryanbackman/zulip,christi3k/zulip,punchagan/zulip,andersk/zulip,kou/zulip,punchagan/zulip,dhcrzf/zulip,Galexrt/zulip,tommyip/zulip,hackerkid/zulip,brainwane/zulip,tommyip/zulip,vaidap/zulip,verma-varsha/zulip,mahim97/zulip,brainwane/zulip,j831/zulip,christi3k/zulip,shubhamdhama/zulip,tommyip/zulip,andersk/zulip,vabs22/zulip,rht/zulip,dhcrzf/zulip,synicalsyntax/zulip,eeshangarg/zulip,timabbott/zulip,christi3k/zulip,jrowan/zulip,timabbott/zulip,Galexrt/zulip,verma-varsha/zulip,j831/zulip,ryanbackman/zulip,zulip/zulip,Galexrt/zulip,andersk/zulip,christi3k/zulip,verma-varsha/zulip,timabbott/zulip,andersk/zulip,rht/zulip,hackerkid/zulip,christi3k/zulip,jrowan/zulip,amanharitsh123/zulip,rishig/zulip,kou/zulip,Galexrt/zulip,synicalsyntax/zulip,timabbott/zulip,rht/zulip,brockwhittaker/zulip,amanharitsh123/zulip,kou/zulip,amanharitsh123/zulip,brockwhittaker/zulip,brockwhittaker/zulip,jphilipsen05/zulip,j831/zulip,andersk/zulip,brockwhittaker/zulip,vaidap/zulip,rht/zulip,christi3k/zulip,zulip/zulip,shubhamdhama/zulip,mahim97/zulip,SmartPeople/zulip,hackerkid/zulip,vabs22/zulip,shubhamdhama/zulip,rishig/zulip,punchagan/zulip