new label function

[Shalucik]

Description

SetImmutableLabels() causes issues with external mutators that patch in labels outside the operators.

The new CombineLabels() function gives operator generic functionality to create a set of labels based on multiple inputs
for setting labels on resources, the input will typically be (obj.Labels, cr.Labels, defaultLabels), combining the resources existing labels, with the cr Labels and a set of operator specific defaultLabels.

Type of change

(Remove irrelevant options)

• Minor change (typo, formatting, version bump)
• New feature
• Improvement of existing feature
• Bugfix
• Refactoring
• Configuration change
• Breaking change

Checklist:

• I've double-checked the code in this PR myself
• I've left the code better than before (boy scout rule)
• The code is readable, comments are added that explain hard or non-obvious parts.
• I've expanded/improved the (unit) tests, when applicable
• I've run (unit) tests that prove my solution works
• There's no sensitive information like credentials in my PR