Nominator: Nominate TX set hashes

[omerfirmak]

This will help scaling to higher TX counts easier. Envelopes wont grow when nominated TX count increases.

Fixes #3211

[codecov[bot]]

Codecov Report

Merging #3216 (e41d687) into v0.x.x (b8521a6) will increase coverage by 33.71%. The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           v0.x.x    #3216       +/-   ##
===========================================
+ Coverage   54.74%   88.45%   +33.71%     
===========================================
  Files         331      167      -164     
  Lines       35753    17062    -18691     
===========================================
- Hits        19572    15092     -4480     
+ Misses      16181     1970    -14211     

Flag	Coverage Δ
integration	31.96% <75.00%> (+1.71%)	:arrow_up:
unittests	87.46% <100.00%> (+0.13%)	:arrow_up:

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
source/agora/test/Base.d	80.31% <ø> (ø)
source/agora/utils/PrettyPrinter.d	99.18% <ø> (-0.01%)	:arrow_down:
source/agora/utils/SCPPrettyPrinter.d	91.72% <ø> (ø)
source/agora/consensus/Ledger.d	97.54% <100.00%> (+0.04%)	:arrow_up:
source/agora/consensus/protocol/Data.d	100.00% <100.00%> (ø)
source/agora/consensus/protocol/Nominator.d	91.71% <100.00%> (+0.81%)	:arrow_up:
source/agora/network/Client.d	94.69% <100.00%> (+4.62%)	:arrow_up:
source/agora/node/Validator.d	92.57% <100.00%> (+1.11%)	:arrow_up:
source/agora/test/FutureEnrollment.d	97.67% <100.00%> (+0.11%)	:arrow_up:
source/agora/common/VibeTask.d	0.00% <0.00%> (-86.67%)	:arrow_down:
... and 178 more

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[hewison-chris]

I triggered re run of failed CI

[hewison-chris]

Needs rebase I think.

[omerfirmak]

All green and rebased