[V8] ShouldHandle, ShouldRetry etc. predicates should have reasonable defaults

[adsamcik]

Currently when using the new API, it is required to specify ShouldHandle predicate for CircuitBreaker, ShouldRetry predicate for Retry and probably more.

I think it would be beneficial to have some reasonable default predicates so that users don't need to specify it every time. For example I would consider reasonable default to handle all requests that throw exceptions (other than OperationCancelledException).

Also it would be nice to have the defaults for Http scenarios (handling 5xx requests), because these will be common as well.

[martintmk]

Yeah, I agree here, let's address this in alpha2. Would provide a nice out-of-box experience.