drafts: Refactor code used to remove drafts.
drafts: Refactor code used to remove drafts.

Adds a `remove_draft` function which deletes the draft and updates the ui
by removing it from the list of drafts.
Also adds comments to increase readability.

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