refactor(cpu-mining): create CpuMiningService

[glevco]

Depends on #802

Motivation

This PR refactors the BaseTransaction.resolve() method, allowing its simulator patch to be removed.

Acceptance Criteria

• Remove resolve() and start_mining() methods from BaseTransaction and from TokenCreationTransaction, moving them to the new CpuMiningService class. Code logic should not be changed, except for the addition of the TokenCreationTransaction case.
• Add CpuMiningService to HathorManager, and update Builder and CliBuilder accordingly.
• Rename simulator/verification.py to simulator/patches.py, adding the new SimulatorCpuMiningService class that overrides resolve().
• Remove all previous patching-related code from Simulator, that now only uses injected customizations.
• Update all usages of resolve() and start_mining().

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: 16 lines in your changes are missing coverage. Please review.

Comparison is base (9150878) 85.09% compared to head (9cbb87e) 85.05%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #803      +/-   ##
==========================================
- Coverage   85.09%   85.05%   -0.05%     
==========================================
  Files         275      276       +1     
  Lines       22516    22514       -2     
  Branches     3434     3430       -4     
==========================================
- Hits        19161    19149      -12     
- Misses       2672     2678       +6     
- Partials      683      687       +4     

Files	Coverage Δ
hathor/builder/builder.py	91.59% <100.00%> (+0.20%)	⬆️
hathor/builder/cli_builder.py	75.12% <100.00%> (+0.25%)	⬆️
hathor/manager.py	82.19% <100.00%> (+0.05%)	⬆️
hathor/simulator/simulator.py	93.38% <100.00%> (-1.10%)	⬇️
hathor/transaction/base_transaction.py	96.13% <100.00%> (+2.10%)	⬆️
hathor/transaction/token_creation_tx.py	99.11% <ø> (-0.04%)	⬇️
hathor/wallet/resources/nano_contracts/execute.py	85.00% <100.00%> (ø)
hathor/wallet/resources/send_tokens.py	98.01% <100.00%> (ø)
hathor/wallet/resources/sign_tx.py	100.00% <100.00%> (ø)
hathor/wallet/resources/thin_wallet/send_tokens.py	68.51% <100.00%> (ø)
... and 2 more

... and 5 files with indirect coverage changes

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The base branch was changed.