[Networking] Refinement of message scope; encapsulating the publish logic in the libp2p node

[yhassanzadeh13]

Introduction

This Pull Request (PR) is a continuation of a larger effort to refactor the networking layer structure within the Flow blockchain, specifically focusing on the removal of the middleware component. It aligns with the strategic approach outlined in Issue #6851.

Objective

The primary goal of this PR is to:

1. Relocate the Publish Logic: Move the Publish logic of pubsub out of the middleware, placing it within the LibP2P Node, and encapsulating the logic entirely at the LibP2P Node level.
2. Enhance the Publish Interface: Refactor the Publish interface of the libp2p node to a higher abstraction level that accepts a single outgoing message scope object, rather than a more tightly coupled interface.

Design Principles

The following software engineering principles guide the changes:

• Encapsulation: By confining the Publish logic to the LibP2P Node level, we are ensuring that the details of the Publish process are hidden from other parts of the system. This promotes modularity and maintainability.
• Abstraction: The introduction of a higher-level Publish interface that accepts a single outgoing message scope object simplifies interaction with the publishing system, offering a clearer and less complex method of operation.
• Atomicity: Allowing the upper-level networking component to pass the entire message being published as a single atomic component down to the libp2p level ensures transaction integrity and reduces the risk of inconsistencies.
• Cohesion: This refactoring strengthens the cohesion within the networking layer, ensuring that related functionalities are kept together, thus making the codebase more understandable and manageable.

Implementation Details

The specific changes are as follows:

• The Publish logic of pubsub has been moved from the middleware to the LibP2P Node.
• The existing Publish interface of the libp2p node has been restructured into a higher-level interface that accepts a single outgoing message scope object.

Benefits

The resulting abstraction provides a safer and more maintainable structure. By adhering to established software engineering principles, this PR contributes to the overall robustness and efficiency of the networking layer.

[codecov-commenter]

Codecov Report

Merging #4635 (5618fa1) into master (68a75a4) will increase coverage by 0.62%.
The diff coverage is 4.12%.

@@            Coverage Diff             @@
##           master    #4635      +/-   ##
==========================================
+ Coverage   54.69%   55.31%   +0.62%     
==========================================
  Files         917      802     -115     
  Lines       85624    72852   -12772     
==========================================
- Hits        46833    40300    -6533     
+ Misses      35197    29243    -5954     
+ Partials     3594     3309     -285     

Flag	Coverage Δ
unittests	55.31% <4.12%> (+0.62%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
cmd/scaffold.go	14.82% <0.00%> (-0.02%)	⬇️
network/p2p/middleware/middleware.go	1.82% <0.00%> (+0.11%)	⬆️
network/p2p/p2pbuilder/libp2pNodeBuilder.go	0.00% <ø> (ø)
network/p2p/test/fixtures.go	30.27% <0.00%> (-1.01%)	⬇️
network/p2p/p2pnode/libp2pNode.go	56.76% <10.52%> (-5.78%)	⬇️

... and 127 files with indirect coverage changes

[gomisha]

LGTM. Please address comments / suggestions before merging.