New Rule Simplify "in dict.keys()" to "in dict"

New Rule Simplify "in dict.keys()" to "in dict": a task in MiMo-V2.6-RL-harbor-code: MiMo-V2.6-RL Code (Harbor) (Harbor dataset). Most of the discussion of the motivation about this rule can be found in this very detailed StackOverflow post (https://stackoverflow.com/a/29314342)