Make the offline prediction latencies configurable by a user

[bkersbergen]

The evaluate_file.rs presents the prediction latencies.

These percentiles that are shown are currently hardcoded.

Make the percentiles configurable using the config file.

in the config file introduce a new section that evaluate_file.rs should use: [evaluation] latency_percentiles = [0, 25, 50, 75, 90, 99.5]