zcash_protocol: Set the public mainnet activation height for NU6

[str4d]

Closes #1356.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 61.32%. Comparing base (d8db481) to head (089905a).
Report is 19 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1548   +/-   ##
=======================================
  Coverage   61.32%   61.32%           
=======================================
  Files         147      147           
  Lines       18667    18667           
=======================================
+ Hits        11447    11448    +1     
+ Misses       7220     7219    -1     

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[daira]

This is blocked on getting the mainnet FPF funding address (which has been requested). I know that this crate doesn't need that address (nor does anything else in librustzcash), but without it the NU6 consensus changes are not well-defined on mainnet.

utACK once that is done.

[str4d]

This is blocked on getting the mainnet FPF funding address

We have that address now: https://github.com/zcash/zcash/pull/6951/files#diff-ff53e63501a5e89fd650b378c9708274df8ad5d38fcffa6c64be417c4d438b6dR253-R255

[nuttycom]

utACK

[daira]

utACK