chore: improve ocpp 1.6 testing

[xBlaz3kx]

Proposed changes

• Moved/nested validation tests in ocpp 1.6 subpackages
• Additional OCPP request/response constructor tests

Types of changes

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• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices apply)

Checklist

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• I have read the CONTRIBUTING doc
• I have signed the CLA
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)
• Any dependent changes have been merged and published in downstream modules

Further comments

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did and what alternatives you considered, etc...

[coveralls]

Coverage Report for CI Build 24960795277

Coverage decreased (-1.6%) to 81.716%

Details

• Coverage decreased (-1.6%) from the base build.
• Patch coverage: 7 uncovered changes across 1 file (3 of 10 lines covered, 30.0%).
• 130 coverage regressions across 26 files.

Uncovered Changes

File	Changed	Covered	%
ocpp1.6/types/security_extension.go	10	3	30.0%

Coverage Regressions

130 previously-covered lines in 26 files lost coverage.

Top 10 Files by Coverage Loss	Lines Losing Coverage	Coverage
ocpp1.6/types/types.go	54	48.28%
ocpp1.6/types/datetime.go	9	61.9%
ocpp1.6/core/stop_transaction.go	7	77.42%
ocpp1.6/types/security_extension.go	6	52.94%
ocpp1.6/core/change_availability.go	4	89.74%
ocpp1.6/core/reset.go	4	89.74%
ocpp1.6/core/status_notification.go	4	89.74%
ocpp1.6/localauth/send_local_list.go	4	90.0%
ocpp1.6/remotetrigger/trigger_message.go	4	89.74%
ocpp1.6/certificates/delete_certificate.go	2	93.55%

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Coverage Stats

Relevant Lines:	8253
Covered Lines:	6744
Line Coverage:	81.72%
Coverage Strength:	11.87 hits per line

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💛 - Coveralls