* feat: calculate retry wait time with exponential back-off
* test: add test for getWaitTime method
* feat: enforce random jitter between min value from previous iteration and current
* extract randomStagger to simplify tests and use Milliseconds to avoid float math.
* rename variables
* add test and rename comment
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Co-authored-by: Poonam Jadhav <poonam.jadhav@hashicorp.com>