Add retry policy for graqhql client

[dduyVeritone]

Background

Often times, we need to retry graphql request in case of transient network issue. This change aims to add that retry capabilities if the library consumers want to.

Overview

• This Pull Request aims to add 2 retry policies for the graphql client:
  • LinearPolicy
  • ExponentialBackoffPolicy
• Included unit test to test the new change

Test

• Added unit test & passed.

[matryer]

This is an excellent PR. Unfortunately, it feels to me like the wrong place to add this functionality. I always like backoff/retry functionality to live outside the client code. I could be convinced otherwise, perhaps we can get some other views? Have you seen this backoff package?

[dahernan]

closing for now