feat(feature-activation): implement must signal

[glevco]

Depends on #800

Motivation

Implement the mandatory signaling mechanism required by the Feature Activation process.

Acceptance Criteria

• Improvements in Builder:
  • Add FeatureService to BuildArtifacts
  • Change implementation of some _get_or_create_* methods so they can all be used without arguments.
  • Change private _get_or_create_settings() and _get_or_create_feature_service() methods to public so they can be used externally (specifically, so the Simulator can properly customize the builder).
• Implement FeatureService.check_must_signal().
• Fix problem in caching mechanism in FeatureService.get_state() caused by must signal verification.
• Remove the original Block.get_feature_activation_bit_counts(), and change calculate_feature_activation_bit_counts() to get_feature_activation_bit_counts().
• Change Block.update_feature_state() to set_feature_state().
• Remove BaseTransaction._update_feature_activation_bit_counts_metadata() as it's not necessary anymore.
• Implement BlockVerifier.verify_mandatory_signaling().

Checklist

• If you are requesting a merge into master, confirm this code is production-ready and can be included in future releases as soon as it gets merged

[codecov]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (bf0d0bc) 84.61% compared to head (b6294a8) 85.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #785      +/-   ##
==========================================
+ Coverage   84.61%   85.00%   +0.38%     
==========================================
  Files         271      271              
  Lines       22311    22362      +51     
  Branches     3406     3416      +10     
==========================================
+ Hits        18878    19008     +130     
+ Misses       2764     2677      -87     
- Partials      669      677       +8     

Files	Coverage Δ
hathor/builder/builder.py	91.10% <100.00%> (-0.21%)	⬇️
hathor/builder/cli_builder.py	74.48% <100.00%> (ø)
hathor/feature_activation/feature_service.py	98.09% <100.00%> (+0.56%)	⬆️
hathor/simulator/simulator.py	94.61% <100.00%> (+0.09%)	⬆️
hathor/transaction/base_transaction.py	94.02% <ø> (-0.13%)	⬇️
hathor/transaction/block.py	94.52% <100.00%> (+0.13%)	⬆️
hathor/transaction/exceptions.py	100.00% <100.00%> (ø)
hathor/transaction/transaction_metadata.py	92.26% <ø> (ø)
hathor/verification/verification_service.py	90.32% <100.00%> (+0.10%)	⬆️
hathor/verification/block_verifier.py	97.14% <88.88%> (-2.86%)	⬇️

... and 7 files with indirect coverage changes

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The base branch was changed.