Enables cancellation on async InjectLatency monkey.

[vany0114]

Hey @reisenberger

I'm honoring the CancellationToken passed thru the execution when we're injecting the latency on the async monkeys to allow latency cancellation.

However, there's an issue with the validations that I put in the previous PR on the Sync policies, more specifically here. Thing is that even when we're not honoring the token in sync latency monkey, the injection of latency doesn't cancel actually (using an optimistic timeout), but when it finish injecting the latency it fails because the token was signaled from timeout policy.

It might be fixed when we implement your propose about allowing the user to decide whether the operation is cancellable or not. However, I was left wondering if we should allow that latency could be canceled even in sync scenarios given that Simmy allows cancellation for the rest of policies, (like Polly does too) I mean, what might be the reason to doesn't allow the user to cancel the latency in sync scenarios?

Thoughts?

Ref: #20

Note: Sorry about formatting diffs.

[reisenberger]

Hey @vany0114 PR looks good for async!

Re:

when we're not honoring the token in sync latency monkey, the injection of latency doesn't [currently] cancel actually (using an optimistic timeout), but when it finish injecting the latency it fails because the token was signaled from timeout policy.

[...] I was left wondering if we should allow that latency could be canceled even in sync scenarios

I agree, good suggestion 👍 to switch to injected sync latency also being cancellable. It makes symmetry between the sync and async cases, which is easier for users to understand.

Like you say, we could later introduce a bool isCancellable option on the InjectLatency policies, as originally discussed in #20.

Sounds good to me!