Create subclasses of JudgeTask for two JudgeTask actions

[lowellrex]

In order to remove the action column from the tasks table, we need to move that information into the various Task models' label methods. In order to support Task classes with multiple actions for a single class we will need to split those into separate classes. This ticket exists to do just that for JudgeTask's assign and review actions (renamed JudgeAssignTask and JudgeReviewTask perhaps?).

This will probably have to be a multi-part release so that we maintain support for existing JudgeTasks. I'd imagine something like the following:

• Stop creating plain JudgeTasks (create either of the two subclasses instead).
• Transform existing JudgeTasks in the database to the appropriate subclass.
• Remove all logic in JudgeTask that relies on the action property (should be handled by subclasses at this point).

Acceptance criteria

• JudgeTasks no longer rely on the tasks.action database column

[lowellrex]

Transformed existing JudgeTasks to appropriate subclasses:

rails c> JudgeReviewTask.count
# 1
rails c> JudgeReviewTask.first.update!(action: nil)

rails c> JudgeTask.where(type: JudgeTask.name).count
# 190

rails c> h = {}
rails c> JudgeTask.where(type: JudgeTask.name).each do |task|
  h[task.action] = 0 unless h.keys.include?(task.action)
  h[task.action] = h[task.action] + 1
end
# {"review"=>89, "assign"=>101}

rails c> JudgeTask.where(type: JudgeTask.name, action: nil).count
# 0

rails c> JudgeTask.where(action: nil).count
# 7

rails c> JudgeTask.where.not(action: nil).count
# 190 = 89 + 101. Great success!

rails c> h = {review: [], assign: [], bad: []}
rails c> JudgeTask.where(type: JudgeTask.name).each do |task|
  case task.action
  when "review"
    h[:review] << task.id
    task.update!(type: JudgeReviewTask.name)
  when "assign"
    h[:assign] << task.id
    task.update!(type: JudgeAssignTask.name)
  else
    h[:bad] << task.id
  end
end
rails c> h
# {:review=>[546, 572, 612, 558, 554, 737, 594, 567, 570, 575, 566, 581, 585, 565, 574, 545, 571, 548, 564, 584, 576, 543, 544, 539, 577, 573, 561, 568, 559, 560, 579, 578, 592, 607, 588, 589, 590, 611, 603, 586, 596, 601, 609, 751, 613, 563, 557, 587, 608, 604, 744, 748, 754, 745, 556, 743, 753, 742, 1432, 562, 606, 739, 580, 569, 1055, 1053, 1057, 1051, 550, 1050, 1183, 1218, 1227, 1244, 1431, 1250, 1220, 749, 1225, 1234, 1240, 1625, 1440, 1443, 1056, 552, 1253, 1215, 1839], :assign=>[1654, 1656, 1655, 1657, 1658, 1659, 1660, 582, 551, 547, 541, 583, 540, 542, 549, 599, 591, 595, 610, 1430, 752, 741, 747, 746, 750, 1433, 1435, 1436, 1437, 1439, 1442, 1444, 1448, 1441, 1446, 1445, 1447, 1438, 1052, 1049, 1059, 1048, 1047, 1061, 1434, 1054, 1060, 1058, 1219, 1221, 1226, 1216, 1228, 1241, 1229, 1230, 1235, 1236, 1238, 1239, 1233, 1243, 1223, 1237, 1231, 1232, 1224, 1217, 1247, 1251, 1254, 1255, 1257, 1258, 1259, 1249, 1256, 1245, 1248, 1252, 1246, 1222, 1653, 1758, 1759, 1760, 1761, 1754, 1755, 1756, 1757, 1753, 1752, 1762, 1763, 1764, 1242, 1844, 1847, 1921, 2014], :bad=>[]}

rails c> JudgeTask.where.not(action: nil).each { |task| task.update!(action: nil) }
rails c> JudgeTask.where.not(action: nil).count
# 0
rails c> JudgeTask.count
# 197