Make Latency monkey no cancellable by configuration

[vany0114]

Currently, all the monkeys are cancellable, which is fine, but we want to allow the user to make the latency monkey no cancellable for those scenarios where even if a token is signaled, they don't want to cancel the latency.

Proposal: add a new property to LatencyOptions/AyncLatencyOptions like this:

internal Func<Context, CancellationToken, Task<bool>> IsCancellable { get; set; }

Might be true by default, then validate it before to honor the token.