lib: fix - invalid timer priority queue order

• in lib/timers.js PriorityQueue.percolateDown cannot be used for rescheduling list, because it does not work in all cases

  • updated item does not have to be root of the heap when new timers are created in runNextTicks and then percolateDown does not solve all binary heap inconsistencies
  • old behavior could cause infinite loop timers in some cases

• added PriorityQueue.updateAt and PriorityQueue.update methods

  • simple implementation by remove & insert, could be improved...
  • rescheduling list uses updateAt method

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• documentation is changed or added
• commit message follows commit guidelines