[Access] Refactor validator into own module

[peterargue]

Issue #7111:
This is part 1 of a series of PRs to refactor common code with /access into separate modules. The goal is to remove cyclical imports resulting from too many common structs being defined in one place.

This PR moves the access.TransactionValidator to its own module.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 81.81818% with 4 lines in your changes missing coverage. Please review.

Project coverage is 41.28%. Comparing base (82d7f1d) to head (ff1300e).

Files with missing lines	Patch %	Lines
cmd/access/node_builder/access_node_builder.go	0.00%	3 Missing ⚠️
integration/internal/emulator/errors.go	75.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7102      +/-   ##
==========================================
+ Coverage   41.25%   41.28%   +0.03%     
==========================================
  Files        2170     2171       +1     
  Lines      190050   190050              
==========================================
+ Hits        78409    78470      +61     
+ Misses     105097   105011      -86     
- Partials     6544     6569      +25     

Flag	Coverage Δ
unittests	41.28% <81.81%> (+0.03%)	⬆️

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[Guitarheroua]

Looks awesome!