refactor: move get settings [part 1]

[glevco]

Motivation

This PR is the first on of a series of PRs focused on improving settings handling in the project, aiming to remove "global settings" that often cause importing order problems and limit varying settings for tests.

Those improvements will be made in two phases:

1. Renaming the HathorSettings() function to get_settings() and removing all invocations from module-level, moving them to inside functions/methods. This will be done incrementally in multiple PRs, and this PR is part 1 of that.
2. Changing all usages of settings to use injection instead of direct access.

Eventually the objective is that get_settings() is only called once in the whole system, and then injected as arguments on all objects/functions that need it.

In this PR, changes are very simple, code is mostly just renamed and the function call is moved. No logic should be changed. The only exceptions are changes to conform to linters and such.

Acceptance Criteria

• Create new get_settings() function that is just a forward of HathorSettings(). This is just so we can do an "incremental rename" without having to touch all code that uses HathorSettings() at once. When it's done, HathorSettings() will be removed.
• Remove some usages of HathorSettings() from the module level and move it to inside functions/methods
  • For functions, the function just calls the new get_settings()
  • For classes we set self._settings = get_settings() in the class' __init__(), and update all methods to use that new attribute

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

Patch coverage: 100.00% and project coverage change: -0.04% ⚠️

Comparison is base (2ebb62f) 84.74% compared to head (2404c82) 84.71%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #768      +/-   ##
==========================================
- Coverage   84.74%   84.71%   -0.04%     
==========================================
  Files         259      259              
  Lines       21940    21933       -7     
  Branches     2964     2964              
==========================================
- Hits        18594    18580      -14     
- Misses       2700     2708       +8     
+ Partials      646      645       -1     

Files Changed	Coverage Δ
hathor/simulator/fake_connection.py	81.62% <ø> (-1.81%)	⬇️
hathor/transaction/__init__.py	100.00% <ø> (ø)
hathor/conf/get_settings.py	71.42% <100.00%> (+1.42%)	⬆️
hathor/p2p/sync_v1/agent.py	85.52% <100.00%> (+0.44%)	⬆️
hathor/p2p/sync_v1/downloader.py	92.02% <100.00%> (+0.04%)	⬆️
hathor/p2p/sync_v2/agent.py	75.83% <100.00%> (-0.88%)	⬇️
hathor/p2p/utils.py	73.87% <100.00%> (ø)
hathor/prometheus.py	89.65% <100.00%> (ø)
hathor/simulator/miner/geometric_miner.py	100.00% <100.00%> (ø)
hathor/simulator/simulator.py	94.64% <100.00%> (ø)
... and 6 more

... and 2 files with indirect coverage changes

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