feat: added support for cloned plugins gated behind --include-plugin-definitions flag

[Prashansa-K]

Gateway 3.15 is adding support for cloned-plugin definitions.
This change ensures that we can manage these entities declaratively
in deck.
For: #2074

Integration tests for gateway are added here.
Konnect related tests would be added once the feature is added on dev.

Test run for gateway: https://github.com/Kong/deck/actions/runs/26811245997/job/79041501704 (some other tests are failing due to schema changes)
(Search via string ClonedPluginDefinitions)

Related:
gdr: Kong/go-database-reconciler#476
go-kong: Kong/go-kong#619

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 47 lines in your changes missing coverage. Please review.
✅ Project coverage is 32.38%. Comparing base (d65cc81) to head (42aa73a).

Files with missing lines	Patch %	Lines
cmd/common.go	0.00%	16 Missing ⚠️
cmd/common_konnect.go	0.00%	8 Missing ⚠️
tests/integration/test_utils.go	0.00%	6 Missing ⚠️
cmd/gateway_dump.go	0.00%	4 Missing ⚠️
cmd/gateway_reset.go	0.00%	4 Missing ⚠️
cmd/gateway_apply.go	0.00%	3 Missing ⚠️
cmd/gateway_diff.go	0.00%	3 Missing ⚠️
cmd/gateway_sync.go	0.00%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2088      +/-   ##
==========================================
- Coverage   32.56%   32.38%   -0.19%     
==========================================
  Files          77       77              
  Lines        7151     7191      +40     
==========================================
  Hits         2329     2329              
- Misses       4626     4666      +40     
  Partials      196      196              

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[Prashansa-K]

Will update this post gdr release

[Prashansa-K]

Konnect APIs aren't available yet. Thus, not waiting on Konnect tests here. They can be added in a different PR.