Add option to fast sync validator during challenge

[amsanghi]

This is being done to avoid waiting for long periods to act if the validator has been restarted during a challenge.

Basically for a fixed set of duration from the start of the node, the validator will act in fast sync mode to allow fast calling of the act function.

[codecov]

Codecov Report

Attention: Patch coverage is 60.00000% with 10 lines in your changes are missing coverage. Please review.

Project coverage is 59.59%. Comparing base (5968270) to head (c59cc7a).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #614      +/-   ##
==========================================
+ Coverage   59.36%   59.59%   +0.22%     
==========================================
  Files          48       48              
  Lines        8234     8256      +22     
==========================================
+ Hits         4888     4920      +32     
+ Misses       3340     3330      -10     
  Partials        6        6              

[rauljordan]

As we no longer act on time ticker, but instead on block notifications, we'll have to revamp this entirely. I'll work on this next, but thanks so much for the original PR here