refactor(core): new pending pkg

[thiagodeev]

This PR moves the pending code in the core pkg into a new core/pending pkg.

Changes made:

• copy/pasted of the pending code from core to core/pending;
• renamed PendingState and PendingStateWriter to State and StateWriter since now the pkg prefix gives the context (e.g: pending.NewState instead of pending.NewPendingState;

[codecov]

Codecov Report

❌ Patch coverage is 75.78125% with 31 lines in your changes missing coverage. Please review.
✅ Project coverage is 75.74%. Comparing base (925371e) to head (691d69c).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
adapters/sn2core/sn2core.go	20.00%	8 Missing ⚠️
core/pending/state.go	77.27%	5 Missing ⚠️
consensus/datasource/consensus_data_source.go	0.00%	4 Missing ⚠️
core/pending/pending.go	86.95%	3 Missing ⚠️
sync/sync.go	50.00%	3 Missing ⚠️
rpc/v8/subscriptions.go	0.00%	1 Missing and 1 partial ⚠️
sync/data_source.go	66.66%	2 Missing ⚠️
sync/helpers.go	66.66%	2 Missing ⚠️
builder/builder.go	90.00%	1 Missing ⚠️
starknetdata/feeder/feeder.go	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3564      +/-   ##
==========================================
+ Coverage   75.72%   75.74%   +0.02%     
==========================================
  Files         384      384              
  Lines       33757    33764       +7     
==========================================
+ Hits        25563    25576      +13     
  Misses       6398     6398              
+ Partials     1796     1790       -6     

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[EgeCaner]

Looks good