Use timeouts in all synthesis rules, we don't want it to hang on a difficult problem

src/main/scala/leon/synthesis/rules/ADTSplit.scala

src/main/scala/leon/synthesis/rules/Cegis.scala

src/main/scala/leon/synthesis/rules/EqualitySplit.scala

src/main/scala/leon/synthesis/rules/Ground.scala

src/main/scala/leon/synthesis/rules/InequalitySplit.scala

src/main/scala/leon/synthesis/rules/OptimisticGround.scala