Fnbool_to_FnOptionT

[rob-solana]

Problem

epoch_vote_states() is clumsy, operates on a bool closure

Summary of Changes

move to Option, more flexible

Fixes #

[garious]

Interesting. I was thinking there was a double-call to get_balance that'd go away as a result of having this.

[garious]

I see it. Need this same change to be made to vote_states().

[codecov]

Codecov Report

Merging #3041 into master will increase coverage by <.1%.
The diff coverage is 92.8%.

@@           Coverage Diff            @@
##           master   #3041     +/-   ##
========================================
+ Coverage    77.2%   77.3%   +<.1%     
========================================
  Files         132     132             
  Lines       20182   20185      +3     
========================================
+ Hits        15599   15606      +7     
+ Misses       4583    4579      -4