Implement label and annotation equality checking (#1467)

[khewonc]

• Implement label and annotation equality checking

• Update pkg/equality/equality_test.go

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What does this PR do?

Cherry pick #1467

Motivation

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Additional Notes

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Minimum Agent Versions

Are there minimum versions of the Datadog Agent and/or Cluster Agent required?

• Agent: vX.Y.Z
• Cluster Agent: vX.Y.Z

Describe your test plan

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Checklist

• PR has at least one valid label: bug, enhancement, refactoring, documentation, tooling, and/or dependencies
• PR has a milestone or the qa/skip-qa label

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 49.12%. Comparing base (59191c6) to head (1fefac4).

Additional details and impacted files

@@            Coverage Diff             @@
##            v1.10    #1470      +/-   ##
==========================================
- Coverage   49.20%   49.12%   -0.08%     
==========================================
  Files         224      224              
  Lines       19701    19699       -2     
==========================================
- Hits         9694     9678      -16     
- Misses       9501     9518      +17     
+ Partials      506      503       -3     

Flag	Coverage Δ
unittests	49.12% <100.00%> (-0.08%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
pkg/equality/equality.go	2.35% <100.00%> (-9.28%)	⬇️

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