Add "last" element handling in nested arrays

[CezarAntohe83]

Description

Our cluster-registry integration, for the Edge GW to CGW migration tools, needs monitoring for various client CRs, during the migration process, especially their CR status, but also other parameters as well.
Sometimes the status is an array of statuses, so we would need to monitor only the last status entry, since that's the valid one for us.
We don't have the length for those arrays apriori, so we cannot call the ServiceMetadataWatcher with:

• objectReference:
  apiVersion: pdm.adobe.io/v1
  kind: RequestProcessing
  name: maia-e2e-test-rp-mircea
  watchedFields:
  • dst: policy_id
    src: spec.authPolicies[X].policyId
    where X is a number, the last in the array, so we would need a "last" string in the watchedFields, to represent the last monitored entry in the array, no matter its length.
    This PR adds the "last" string in the CR handling.

Related Issue

Motivation and Context

How Has This Been Tested?

Screenshots (if appropriate):

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:

• I have signed the Adobe Open Source CLA.
• 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.

[victorvarza]

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