feat: brokers can be added to event lineage graph

[Cali0707]

Fixes #7681

Proposed Changes

• Create graph method to add a broker to the graph
• Add some comparable types and conversion functions to use in testing, as edges aren't comparable

Pre-review Checklist

• At least 80% unit test coverage
• E2E tests for any new behavior
• Docs PR for any user-facing impact
• Spec PR for any new API feature
• Conformance test for any change to the spec

Release Note

Brokers are now supported in the event lineage graph

Docs

[knative-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Cali0707

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[Cali0707]

/cc @Leo6Leo @pierDipi @creydr

[codecov]

Codecov Report

Attention: Patch coverage is 90.00000% with 5 lines in your changes are missing coverage. Please review.

Project coverage is 69.11%. Comparing base (a154f1a) to head (4317b0d).
Report is 7 commits behind head on main.

Files	Patch %	Lines
pkg/graph/types.go	76.19%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7731      +/-   ##
==========================================
+ Coverage   69.04%   69.11%   +0.06%     
==========================================
  Files         338      339       +1     
  Lines       19350    19398      +48     
==========================================
+ Hits        13360    13406      +46     
- Misses       5328     5330       +2     
  Partials      662      662              

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[Leo6Leo]

Overall looks good to me! just left few questions

[Leo6Leo]

go imports problem

[Leo6Leo]

/lgtm