Limiting max retry delay when using standard backoff types

[juraj-blazek]

With current API it's not possible to limit max retry delay while using built-in backoff types.

We have a scenario where we infinitely retry failing background operations until recovery. Once the failures start, we want to backoff exponentially using the built-in generators, but eventually limit the calculated delay to some maximum value.

Consider adding TimeSpan MaxRetryDelay? property to the retry options that will cap the generated delay value. It might be applicable both for built-in and externally provided delay generators.

cc @martintmk

[martintmk]

I think this is a valid scenario. The changes should be relatively small so we can still squeeze this into v8.

Minor comments only:

• MaxRetryDelay should be MaxDelay - because we have the Delay property
• Maybe not apply the cap on external generators? (as the generation is fully under their control)

cc @martincostello