Resolve "Refactor how PNDs are implemented in the code"

Description

Related Issue

Motivation and Context

How Has This Been Tested?

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Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

Closes #243

controller/interfaces/networkelement/networkElement.go

@@ -25,6 +25,7 @@ type NetworkElement interface {
 	GetModelAsString() (string, error)
 	TransportAddress() string
 	GetMetadata() conflict.Metadata
+	PndID() uuid.UUID
 }
 
 // Details contains details of a network element used by the cSBI mechanism.