RPC: Rework to implement a packet based protocol

[omerfirmak]

This will allow us to have multiple requests in-flight on a single connection and allow infinite nested RPC requests

[omerfirmak]

Fixes #3253

[codecov[bot]]

Codecov Report

Merging #3276 (da072e1) into v0.x.x (34af95e) will increase coverage by 1.44%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           v0.x.x    #3276      +/-   ##
==========================================
+ Coverage   87.72%   89.17%   +1.44%     
==========================================
  Files         164      165       +1     
  Lines       16976    17038      +62     
==========================================
+ Hits        14893    15193     +300     
+ Misses       2083     1845     -238     

Flag	Coverage Δ
integration	33.51% <100.00%> (?)
unittests	87.93% <0.00%> (+0.20%)	:arrow_up:

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

Impacted Files	Coverage Δ
source/agora/network/Client.d	93.27% <ø> (+6.15%)	:arrow_up:
source/agora/node/Runner.d	55.55% <ø> (+55.55%)	:arrow_up:
source/agora/network/RPC.d	54.54% <100.00%> (+53.03%)	:arrow_up:
source/agora/network/VibeManager.d	47.82% <100.00%> (+46.39%)	:arrow_up:
source/agora/node/Validator.d	91.45% <0.00%> (-0.97%)	:arrow_down:
source/agora/consensus/state/Ledger.d	90.26% <0.00%> (-0.68%)	:arrow_down:
source/agora/consensus/protocol/Nominator.d	91.63% <0.00%> (-0.36%)	:arrow_down:
source/agora/script/Engine.d	97.59% <0.00%> (-0.16%)	:arrow_down:
source/agora/node/main.d	44.85% <0.00%> (ø)
source/agora/network/Manager.d	79.50% <0.00%> (+0.93%)	:arrow_up:
... and 10 more

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