Add benchmark for time prediction about finderouter

[Coding-Enthusiast]

This is partially solved in 221ac33 and 07e6a5f
This new feature prints an estimated speed (number of permutations checked per second) and the time remaining to process all cases every couple of seconds (3 to be exact).

Although this method is accurate, the first value requires at least one round (in the outer loop) to finish which would update the Progress property used in its calculations. In cases where the total keys to check is huge, this can take a considerable amount of time before the estimated values starts showing up.
This means we still need a benchmark feature to know how many permutations can the user's computer process per second to give an initial time and speed prediction, then update it later using the exact values using the Progress property.