refactor(stratum): Build StratumFactory on builder

[msbrogli]

Acceptance criteria

1. Build StratumFactory in the builders.
2. Listen to TCP port only on run_node cli command.

[codecov]

Codecov Report

Merging #619 (9ba84cc) into master (33fb275) will decrease coverage by 0.04%.
The diff coverage is 81.81%.

@@            Coverage Diff             @@
##           master     #619      +/-   ##
==========================================
- Coverage   83.66%   83.62%   -0.04%     
==========================================
  Files         232      232              
  Lines       19781    19788       +7     
  Branches     2707     2707              
==========================================
- Hits        16550    16548       -2     
- Misses       2634     2640       +6     
- Partials      597      600       +3     

Impacted Files	Coverage Δ
hathor/builder/cli_builder.py	70.43% <20.00%> (-1.40%)	⬇️
hathor/builder/builder.py	91.11% <100.00%> (+0.24%)	⬆️
hathor/manager.py	70.64% <100.00%> (-0.27%)	⬇️
hathor/stratum/stratum.py	69.13% <100.00%> (-0.19%)	⬇️

... and 4 files with indirect coverage changes

[glevco]

I'm approving this, but I left two suggestion comments. I guess they could be done in the future, so feel free to resolve the threads.