feat(reactor): implement option to use asyncio reactor

[glevco]

Depends on #888

Motivation

Considering the general improvements we plan to make in the full node related to concurrent and parallel execution, using async/await and multiprocessing, it may be useful to interop with Python's native asyncio. Currently we used Twisted's default reactor, but they provide a reactor that has compatibility with asyncio: AsyncioSelectorReactor. In theory, it is a drop-in replacement for what we're currently using.

This PR adds an experimental CLI option to enable this custom reactor, so we can test its usage in some full nodes for a while. Then, we'll have data to assess whether it's worth it using it as the default, in the future.

Acceptance Criteria

• Add --x-asyncio-reactor CLI option to enable using the asyncio reactor.
• Update get_global_reactor() to add support for installing the asyncio reactor.
• Add reactor type to initial logs.

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 (27381c1) 85.35% compared to head (15ba731) 85.34%.
Report is 1 commits behind head on master.

❗ Current head 15ba731 differs from pull request most recent head e84f95d. Consider uploading reports for the commit e84f95d to get more accurate results

Files	Patch %	Lines
hathor/reactor/reactor.py	63.33%	8 Missing and 3 partials ⚠️
hathor/websocket/factory.py	71.42%	2 Missing ⚠️
hathor/debug_resources.py	66.66%	1 Missing ⚠️
hathor/stratum/stratum.py	80.00%	1 Missing ⚠️
hathor/wallet/resources/thin_wallet/send_tokens.py	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #889      +/-   ##
==========================================
- Coverage   85.35%   85.34%   -0.01%     
==========================================
  Files         282      284       +2     
  Lines       22280    22443     +163     
  Branches     3366     3396      +30     
==========================================
+ Hits        19018    19155     +137     
- Misses       2592     2604      +12     
- Partials      670      684      +14     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

The base branch was changed.