refactor(sync-v2): implement P2PStorage and P2PVertexHandler [part 9/12]

[glevco]

Depends on #1023

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Motivation

This PR begins a refactor in Sync-v2 that will allow it to work asynchronously, meaning it can receive and download vertices from other peers even if previously received vertices have not been verified, through the consensus, and saved yet. This is necessary for the Multiprocess Verification project.

In order to do this, each agent saves received vertices in a memory storage local to only that agent. After a vertex completes the pipeline, it is saved in the persisted TransactionStorage and removed from the agent-specific memory storage.

This PR introduces the P2PStorage class, which is an abstraction layer over the TransactionStorage, and in the next PR an async version of this class will be implemented with in-memory capabilities. This is done by providing two method versions for each storage method that is used by Sync-v2: one "local" and one "non-local". Generally speaking, when downloading vertices, an agent uses "local" methods — meaning it can use its in-memory data to advance the sync. Conversely, when uploading vertices, the agent uses "non-local" methods, which are simply a forward to the persisted storage.

A similar abstraction is introduced for VertexHandler, by the P2PVertexHandler class. It is a single point of contact for Sync-v2 when handling new vertices.

Acceptance Criteria

• Implement P2PStorage, an abstraction over TransactionStorage and indices to be used in Sync-v2.
• Implement P2PVertexHandler, and abstraction over VertexHandler to be used in Sync-v2.
• Update all Sync-v2 calls to the storage to use the respective equivalent P2PStorage method.
• Move BaseTransaction.can_validate_full to the storage.
• Update typings in the traversal module so it can receive the more generic VertexStorageProtocol instead of a TransactionStorage.

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

[glevco]

Shouldn't we return False here?

[codecov]

Codecov Report

Attention: Patch coverage is 92.12598% with 10 lines in your changes are missing coverage. Please review.

Project coverage is 84.67%. Comparing base (8416913) to head (bfc28b4).

Files	Patch %	Lines
hathor/transaction/storage/transaction_storage.py	75.00%	2 Missing and 2 partials ⚠️
hathor/p2p/sync_v2/agent.py	90.00%	0 Missing and 3 partials ⚠️
hathor/p2p/sync_v2/p2p_storage.py	95.65%	2 Missing ⚠️
hathor/manager.py	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@                           Coverage Diff                            @@
##           refactor/verification-dependencies-8    #1024      +/-   ##
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+ Coverage                                 84.66%   84.67%   +0.01%     
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  Files                                       302      304       +2     
  Lines                                     23146    23184      +38     
  Branches                                   3515     3515              
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+ Hits                                      19596    19631      +35     
- Misses                                     2865     2868       +3     
  Partials                                    685      685              

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