MBS-3663: extend expiration of edits that receive 'No' votes, and give editors time to respond in the case of unanimous 'No' votes

So, this patch does two things.

1. when an edit goes from having 0 to having 1 'no' vote, ensure that the original editor has sufficient time to respond, at present defined as 72 hours. Therefore, if the edit expiration time is less than 72 hours in the future, set it to 72 hours from now.

2. when an edit would expire from three unanimous 'no' votes, ensure that the original editor has sufficient time to respond (again, 72 hours). Therefore, filter the list of edits for modbot to exclude any edit where the time since the first non-superseded no vote is less than 72 hours in the past.

Open question: answered! Making emails work like I made the expiration extension work.

Update: remove cruft

Update 2: make email/edit extension work the same and update Data::Vote tests.

Update 3: Add more tests, change to a DateTime::Duration instead of a number of hours alone.

Update 4: reword email, move formatting out of constants file.