Consider setting CPU affinity for fdbserver processes

From https://forums.foundationdb.org/t/setting-cpu-affinity-for-fdbservers/84, it was noted that we don't set CPU affinity for any of the processes we start, and there's likely advantages to doing so. It appears once upon a time, we had code in the resolver that would pin itself to a core, but it was commented out, and I agree doing it from fdbmonitor sounds like a better solution.

Implementing this doesn't sound like too much work, and a quick run through a performance test should tell us if it makes any noticeable impact.

Start with fdbmonitor, which the issue identifies as the preferred place to set CPU affinity for processes it starts, and review the previously commented-out resolver affinity code for context. Run the project's performance test after implementing the behavior and confirm whether CPU affinity produces a noticeable impact.

Written by the indexing model from the issue text.