refactor(p2p): implement initial state [part 8/11]

[glevco]

Depends on #1142

Motivation

This PR addresses a few architectural shortcomings in the handling of protocol states in P2P. Currently:

• The HathorProtocol.state attribute is Optional and starts as None, instead of having a well-defined initial state.
• We store unused state instances indefinitely.
• The state machine does not specify which state comes after another.
• There are two types for tracking current state: the PeerState enum and the BaseState subclasses themselves.
• We only start tracking HathorProtocol instances after they get connected, but it's useful to track them since construction. Specifically, this will be necessary for the P2P Multiprocess project.

Acceptance Criteria

• Implement new P2P InitialState and change HathorProtocol.state to be non-nullable.
• Remove PeerState.
• Add new built_protocol_callback on P2P protocol factory and use it to track built protocol instances in PeerConnections.
• Implement missing PeerAddress.__hash__ override to consider localhost.

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: Patch coverage is 94.95798% with 6 lines in your changes missing coverage. Please review.

Project coverage is 84.87%. Comparing base (bf1e568) to head (659806b).

Files with missing lines	Patch %	Lines
hathor/p2p/states/base.py	84.61%	2 Missing ⚠️
hathor/p2p/dependencies/protocols.py	0.00%	0 Missing and 1 partial ⚠️
hathor/p2p/factory.py	87.50%	0 Missing and 1 partial ⚠️
hathor/p2p/states/peer_id.py	91.66%	1 Missing ⚠️
hathor/p2p/states/ready.py	88.88%	1 Missing ⚠️

Additional details and impacted files

@@                       Coverage Diff                       @@
##           refactor/p2p/remove-manager    #1172      +/-   ##
===============================================================
+ Coverage                        84.72%   84.87%   +0.14%     
===============================================================
  Files                              320      321       +1     
  Lines                            24457    24498      +41     
  Branches                          3718     3728      +10     
===============================================================
+ Hits                             20721    20792      +71     
+ Misses                            3004     2987      -17     
+ Partials                           732      719      -13     

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