Backport slow node avoidance to driver 3

The "slow node avoidance" algorithm was introduced in DSE driver 2 () then introduced in OSS driver 4.5, thanks to the "drivers unification".

We would like to backport this algorithm to OSS driver 3 then DSE driver 1.

Since it serves roughly the same purpose as other latency-based algorithms such as LatencyAwarePolicy, but with better results, we could introduce it in driver 3 as a new, chainable policy that would be a drop-in replacement for LatencyAwarePolicy.