feat(feature-activation): implement signal bits in mining blocks

[glevco]

Motivation

This PR implements the BitSignalingService usage as defined in this RFC.

Acceptance Criteria

• Add BlockTemplate.signal_bits attribute
• Add BitSignalingService to HathorManager and use it to inject signal_bits into mining blocks
• Add Feature Activation related methods to Builder and CliBuilder
• Add Builder.set_settings() method, which is useful for testing

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

Merging #703 (f89cd71) into master (4277cc2) will increase coverage by 0.04%.
Report is 4 commits behind head on master.
The diff coverage is 81.11%.

@@            Coverage Diff             @@
##           master     #703      +/-   ##
==========================================
+ Coverage   84.62%   84.67%   +0.04%     
==========================================
  Files         253      252       -1     
  Lines       21708    21770      +62     
  Branches     2941     2948       +7     
==========================================
+ Hits        18371    18434      +63     
+ Misses       2702     2690      -12     
- Partials      635      646      +11     

Files Changed	Coverage Δ
hathor/p2p/utils.py	73.87% <66.66%> (-1.40%)	⬇️
hathor/simulator/fake_connection.py	83.42% <70.00%> (-0.76%)	⬇️
hathor/builder/builder.py	91.51% <80.00%> (-1.49%)	⬇️
hathor/builder/cli_builder.py	74.48% <100.00%> (+0.53%)	⬆️
hathor/manager.py	82.76% <100.00%> (+0.07%)	⬆️
hathor/mining/block_template.py	94.33% <100.00%> (+5.87%)	⬆️
hathor/p2p/resources/status.py	100.00% <100.00%> (ø)
hathor/p2p/states/ready.py	93.89% <100.00%> (-0.05%)	⬇️
hathor/simulator/miner/geometric_miner.py	100.00% <100.00%> (ø)
hathor/transaction/base_transaction.py	93.99% <100.00%> (+<0.01%)	⬆️

... and 5 files with indirect coverage changes