refactor(plan): reduce Calculate() cyclomatic complexity

[vflaux]

What does it do ?

Reduce plan.Calculate() cyclomatic complexity (was 32).

plan.Calculate() is split into 3 new functions:

• plan.appendTakenDNSNameChanges
• plan.calculatePlanTableRowChanges
• plan.appendEndpointUpdates

Motivation

#5419

More

• Yes, this PR title follows Conventional Commits
• Yes, I added unit tests
• Yes, I updated end user documentation accordingly

[coveralls]

Pull Request Test Coverage Report for Build 19599004118

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 4 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+0.009%) to 78.677%

---

Files with Coverage Reduction	New Missed Lines	%
openshift_route.go	1	79.49%
plan.go	3	95.85%

Totals
Change from base Build 19598374265:	0.009%
Covered Lines:	15969
Relevant Lines:	20297

---

💛 - Coveralls

[mloiseleur]

Thanks, it LGTM.
See my suggestion for a minor nitpick.

[mloiseleur]

/lgtm

[ivankatliarchuk]

/approve

[k8s-ci-robot]

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