[CONTENT] Re-implement setInterval/setTimeout code into tasks

[Jameskmonger]

• npc random movement (Actor.initiateRandomMovement)
• anti-spam eating (rs:eating)
• ladders (rs:ladders)
• taverly dungeon ladder (rs:taverly_dungeon_ladder)
• pickables (rs:pickables)
• prospecting (rs:prospecting)
• sheep shearing (rs:sheep_shearing)
• looting crates (rs:crates)
• mill hopper (rs:grain_hopper and rs:grain_hopper_controls)
• Falador guards talking to eachother (promises:custom_guards)
• Sheep saying "baa" (rs:sheep_shearing) (depends on [ENGINE] Create task to handle NPCs shouting regularly #415)